904 resultados para bioactivity-directed isolation


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The prevalence of Mycobacterium bovis and other mycobacterial species in livestock specimens and milk was evaluated. An emphasis was placed upon the distribution of these organisms in milk that is readily available to the public that was either untreated, pasteurized, or treated using ultra high temperature. Twenty-two pathologic specimens from livestock (bovine, swine and bubaline) in five Brazilian states and 128 bovine milk samples from retail markets in the State of São Paulo were examined for mycobacteria. Identification was made by classical biochemical tests, thin layer chromatography of mycolic acids and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Mycobacteria were isolated from 15 (68.2%) caseous lesions and from 23 (18%) milk samples. Eleven isolates were identified as M. bovis, and the remaining 27 nontuberculous mycobacterial isolates were represented by five species and six unidentified rapidly growing mycobacterial strains. The data demonstrate that animal products in Brazil are frequent reservoirs of mycobacteria and may pose a risk to the public.

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A obtenção de marcas genéticas, quer sejam para resistência a drogas, quer para auxotrofia, é uma etapa trabalhosa mas importante em pesquisa genética. Esse trabalho visou a obtenção de mutantes auxotróficos de Trichoderma harzianum utilizando-se a técnica de enriquecimento por filtração. A técnica mostrou-se superior à técnica convencional de isolamento total. Doze mutantes auxotróficos obtidos foram testados quanto a estabilidade, crescimento e resistência ao fungicida benomil. Eles apresentaram taxas de crescimento e esporulação comparáveis à linhagem parental e dois mutantes foram resistentes a benomil em uma concentração de 500µg/ml.

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

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

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Do total de 622 amostras de fezes, sendo 200 de suínos, 220 de bezerros e 202 de cães, Campylobacter foi isolado em 178 amostras. Destas, o agente foi identificado em 64 (36%) amostras, isoladas somente em meio seletivo de Butzler (MSB); em 34 (19%) o microorganismo foi isolado a partir da técnica de filtração (TF) e em 80 (45%), através de ambos os procedimentos (MSB+TF). A comparação entre as proporções de positividade, pelas diferentes técnicas, revelou significância (c2 = 9.184; p > 0,001) sendo a MSB (36%) a mais eficiente comparada com a TF (19%) O uso associado de ambos os procedimentos proporcionou a positividade mais elevada de isolamento com 45%.

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Aqueous infusions of Brazilian Maytenus leaves are used as beverages, foodstuffs, and phytomedicines. Previously, we isolated two new flavonoid tetrasaccharides from the infusion of Maytenus aquifolium leaves that showed antiulcer activity. In this investigation a new flavonoid tetrasaccharide, kaempferol-3-O-alpha -L-rhamnopyranosyl (1-6)-O-[alpha -L-arabinopyranosyl (1 -->3)-O-alpha -L-rhamnopyranosyl (1-2)]-O-beta -D-galactopyranoside (3), was isolated, together with kaempferol tri- and disaccharides and quercetin trisaccharides from the aqueous infusion of Maytenus ilicifolia leaves. All structures were elucidated by ES-MS and NMR spectroscopic methods. The quantitative analysis of the flavonoid glycosides from Maytenus ilicifolia and M. aquifolium has been performed by HPLC.

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The purpose of this study was to isolate yeast (Candida) from the quarter milk of cow udders from 37 dairy farms in Brazil and to identify the different species involved in mastitis. The samples were collected between October 2002 and February 2003. Two-hundred-and-sixty milk samples from cows with clinical and subclinical mastitis were examined. Milk samples were plated onto Blood agar, Mac Conkey agar and Sabouraud dextrose agar. Forty-five (17.3%) samples were positive for the genus Candida. The Candida species isolated were C. krusei (44.5%), C. rugosa (24.5%), C. albicans (8.9%), C. guilliermondii (8.9%), and others (13.2%). We also isolated Escherichia coli (26.5%), coagulase-positive Staphylococcus (25.0%), Streptococcus spp. (8.1%), Enterobacter spp. (8.1%), and other fungi (8.1%), among others.

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Glycogenin acts in the initiation step of glycogen biosynthesis by catalyzing a self-glucosylation reaction. In a previous work [de Paula et al., Arch. Biochem. Biophys. 435 (2005) 112-124], we described the isolation of the cDNA gnn, which encodes the protein glycogenin (GNN) in Neurospora crassa. This work presents a set of biochemical and functional studies confirming the GNN role in glycogen biosynthesis. Kinetic experiments showed a very low GNN K-m (4.41 mu M) for the substrate UDP-glucose. Recombinant GNN was produced in Escherichia coli and analysis by mass spectroscopy identified a peptide containing an oligosaccharide chain attached to Tyr196 residue. Site-directed mutagenesis and functional complementation of a Saccharomyces cerevisiae mutant strain confirmed the participation of this residue in the GNN self-glucosylation and indicated the Tyr198 residue as an additional, although less active, glucosylation site. The physical interaction between GNN and glycogen synthase (GSN) was analyzed by the two-hybrid assay. While the entire GSN was required for full interaction, the C-terminus in GNN was more important. Furthermore, mutation in the GNN glucosylation sites did not impair the interaction with GSN. (c) 2005 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

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This work deals with the synthesis, spectroscopic and structural investigation of pyrazolyl complexes of the type trans-[M(NCS)(2)(HPz)(4)] {M=Co (1), Ni (2); HPz=pyrazole}. Single crystal X-ray studies on 1 and 2 reveal the formation of similar supramolecular arrangements derived from self-assembly of monomers linked together through intermolecular N-H center dot center dot center dot SCN hydrogen bonds, C-H center dot center dot center dot pi interactions and pi-pi stacking. (c) 2005 Elsevier B.V. All rights reserved.

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Curtobacterium wilt has become an important disease of beans in several localities in the country. Its causal agent, Curtobacterium flaccumfacciens pv. flaccumfaciens (Cff), survives and is disseminated through seeds. To date, few studies have been conducted with the objective of developing an effective and low-cost culture medium to isolate this bacterium from bean seeds, for health analysis purposes. Usually, the culture media employed for coryneform bacteria isolation contain specific carbon sources and antimicrobial products not available in the Brazilian market. A culture medium known as MSCFF was developed (peptone - 5 g, meat extract - 3 g, sucrose - 5 g, agar 15 g, skim milk powder* - 5 g. Congo red* - 0.05 g-, chlorothalonil* - 0.01 g, thiophanate methyl* - 0.01 g, nalidixic acid* - 0.01 g, nitrofurantoin* - 0.01 g. oxacillin* 0.001 g, sodium azide* - 0.001 g and distilled water q.s. 1L; *added after autoclaving the basal medium), which has the ability to inhibit growth of a large amount of saprophytic bacteria, but with low supressivity to Cff isolates. The MSCFF medium was highly effective for Cff isolation from naturally infected bean seeds and could be used for routine detection of this bacterium in bean seeds.

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The bioassay directed fractionation of the EtOH extract from leaves of Cryptocarya ashersoniana seedlings led to the isolation of two flavonol glucosides: iso-quercitrin and hyperin, which exhibited free radical scavenging activity towards DPPH (IC50 34.4 muM and 32.7 muM, respectively) and were compared to standard compounds rutin (IC50 27.0 muM) and catechin (IC50 41.4 muM). Investigation of extracts from the seedlings roots and stems afforded one antifungal styrylpyrone: goniothalamine, and two dihydropyrones: 6-propyl-5,6-dihydro-2-pyrone and the new 6-[(4'-ethyl-9'-oxabicyclo[3.3.1]non-6'-en-3'-yl)methyl]-5,6-dihydro-2H-pyran-2-one, which had its structure determined by detailed analysis of MS and NMR data, including 2D experiments.