117 research outputs found
Efeitos de restos culturais de milho sobre o crescimento de plantas de cafeeiro (Coffea arabica L.)
Quantificação de sorgoleone em extratos e raízes de sorgo sob diferentes períodos de armazenamento
Extracellular matrix formation enhances the ability of streptococcus pneumoniae to cause invasive disease
Extent: 17p.During infection, pneumococci exist mainly in sessile biofilms rather than in planktonic form, except during sepsis. However, relatively little is known about how biofilms contribute to pneumococcal pathogenesis. Here, we carried out a biofilm assay on opaque and transparent variants of a clinical serotype 19F strain WCH159. After 4 days incubation, scanning electron microscopy revealed that opaque biofilm bacteria produced an extracellular matrix, whereas the transparent variant did not. The opaque biofilm-derived bacteria translocated from the nasopharynx to the lungs and brain of mice, and showed 100- fold greater in vitro adherence to A549 cells than transparent bacteria. Microarray analysis of planktonic and sessile bacteria from transparent and opaque variants showed differential gene expression in two operons: the lic operon, which is involved in choline uptake, and in the two-component system, ciaRH. Mutants of these genes did not form an extracellular matrix, could not translocate from the nasopharynx to the lungs or the brain, and adhered poorly to A549 cells. We conclude that only the opaque phenotype is able to form extracellular matrix, and that the lic operon and ciaRH contribute to this process. We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease.Claudia Trappetti, Abiodun D. Ogunniyi, Marco R. Oggioni and James C. Pato
Water‐Soluble Phytotoxic Substances in Alfalfa Forage: Variation with Variety, Cutting, Year, and Stage of Growth 1
Presence and Persistence of Phytotoxic Substances in Wheat, Oat, Corn, and Sorghum Residues 1
Soil‐Applied Atrazine Alters Blue Grama Physiology and Indirectly Influences Soil Nitrogen
Stereochemical consequences of dynamic gearing in substituted bi(9-triptycyl)methanes and related molecules
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