Comparison of flagellin genes from clinical and environmental Pseudomonas aeruginosa isolates.
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Pseudomonas aeruginosa, an important opportunistic pathogen, was isolated from environmental samples and compared to clinically derived strains. While P. aeruginosa was isolated readily from an experimental mushroom-growing unit, it was found only rarely in other environmental samples. A flagellin gene PCR-restriction fragment length polymorphism analysis of the isolates revealed that environmental and clinical P. aeruginosa strains are not readily distinguishable. The variation in the central regions of the flagellin genes of seven of the isolates was investigated further. The strains used included two strains with type a genes (998 bp), four strains with type b genes (1,258 bp), and one strain, K979, with a novel flagellin gene (2,199 bp). The route by which flagellin gene variation has occurred in P. aeruginosa is discussed. (+info)
LB-AUT7, a novel symbiosis-regulated gene from an ectomycorrhizal fungus, Laccaria bicolor, is functionally related to vesicular transport and autophagocytosis.
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We have identified LB-AUT7, a gene differentially expressed 6 h after ectomycorrhizal interaction between Laccaria bicolor and Pinus resinosa. LB-Aut7p can functionally complement its Saccharomyces cerevisiae homolog, which is involved in the attachment of autophagosomes to microtubules. Our findings suggest the induction of an autophagocytosis-like vesicular transport process during ectomycorrhizal interaction. (+info)
Ultrastructure of an indigotin-producing dome mutant of Schizophyllum commune.
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Electron microscopic observations of an indigotin-producing dome mutant of Schizophyllum commune Fr. have shown that large wall ingrowths occur within the hyphae. These ingrowths are coupled with morphological abnormalities produced by the dome mutation. The pigment indigotin appears to be produced by progressive condensation within vacuoles and to a lesser extent within the wall ingrowths. Cytochemical techniques have shown that the wall ingrowths are similar in structure to the hyphal walls. there was no evidence for the passage of condensed indigotin into the medium; the pigment granules found in the medium must therefore form outside the hyphae. (+info)
Studies on basidiospore development in Schizophyllum commune.
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The time required for synthesis of the spore components and the effect of different environmental conditions on basidiospore production were studied in the basidiomycete Schizophyllum commune. Both exogenous glucose and storage materials were used in the synthesis of spore components, which took 40 to 45 h to complete. A temperature of 30 degrees C, the presence of 5% CO2, a continuous supply of glucose, or a lack of exogenous glucose, had no effect on the rate of spore production. Light, however, was required for sporulation. Darkness inhibited sporulation between karyogamy and the initiation of meiosis: complete inhibition occurred after 48 h in the dark. Spores were produced 5 h after release from dark inhibition. (+info)
Hypersensitivity pneumonitis among workers cultivating Tricholoma conglobatum (shimeji).
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We report five cases of hypersensitivity pneumonitis among workers cultivating Tricholoma conglobatum (shimeji). After having worked for 5 to 20 years, they began to notice symptoms of cough, sputum, and dyspnea. They were diagnosed as having a hypersensitivity pneumonitis based on clinical features, bronchoalveolar lavage and transbronchial lung biopsy. By the double immunodiffusion test, precipitating lines between shimeji spore antigen and sera were observed in all of the patients. By enzyme-linked immunosorbent assay, the antibody activities against shimeji and three species of fungi (Cladosporium sphaerospermum, Penicillium frequentans, and Scopulariopsis species) were significantly higher in the sera of the patients than in those of normal subjects who were cultivating shimeji. Although it is not clear what causes this disease, these findings may be helpful in determining the specific antigen. (+info)
Purification and characterization of an anti-(A+B) specific lectin from the mushroom Hygrophorus hypothejus.
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A lectin (HHL) was isolated from the fruiting body of the mushroom Hygrophorus hypothejus by a combination of affinity chromatography on stromas of group B erythrocytes embedded in polyacrylamide gel, and DEAE-trisacryl and gel filtration chromatography. Its molecular mass, as determined by gel filtration, is estimated to be 68000 kDa and its structure is tetrameric with four identical subunits assembled with non-covalent bonds. HHL agglutinates specifically A and B blood group erythrocytes and in hemagglutination inhibition assays, exhibits sugar-binding specificity toward lactose, the anomeric alpha form being more effective than the beta form. (+info)
Striking activation of oxidative enzymes suspended in nonaqueous media.
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The catalytic activity of four lyophilized oxidative enzymes-horseradish peroxidase, soybean peroxidase, Caldariomyces fumago chloroperoxidase, and mushroom polyphenol oxidase-is much lower when directly suspended in organic solvents containing little water than when they are introduced into the same largely nonaqueous media by first dissolving them in water and then diluting with anhydrous solvents. The lower the water content of the medium, the greater this discrepancy becomes. The mechanism of this phenomenon was found to arise from reversible denaturation of the oxidases on lyophilization: because of its conformational rigidity, the denatured enzyme exhibits very limited activity when directly suspended in largely nonaqueous media but renatures and thus yields much higher activity if first redissolved in water. Two independent means were discovered for dramatically minimizing the lyophilization-induced inactivation, both involving the addition of certain types of excipients to the aqueous enzyme solution before lyophilization. The first group of excipients consists of phenolic and aniline substrates as well as other hydrophobic compounds; these presumably bind to the hydrophobic pocket of the enzyme active site, thereby preventing its collapse during dehydration. The second group consists of general lyoprotectants such as polyols and polyethylen glycol that apparently preserve the overall enzyme structure during dehydration. The activation effects of such excipients can reach into the tens and hundreds of fold. Moreover, the activations afforded by the two excipient groups are additive, resulting in up to a complete protection against lyophilization-induced inactivation when representatives of the two are present together. (+info)
Multi-specificity of a Psathyrella velutina mushroom lectin: heparin/pectin binding occurs at a site different from the N-acetylglucosamine/N-acetylneuraminic acid-specific site.
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An N-acetylglucosamine (GlcNAc)/N-acetylneuraminic acid-specific lectin from the fruiting body of Psathyrella velutina (PVL) is a useful probe for the detection and fractionation of specific carbohydrates. In this study, PVL was found to exhibit multispecificity to acidic polysaccharides and sulfatides. Purified PVL and a counterpart lectin to PVL in the mycelium interact with heparin neoproteoglycans, as detected by both membrane analysis and solid phase assay. The pH-dependencies of the binding to heparin and GlcNAc5-6 differ. The heparin binding of PVL is inhibited best by pectin, polygalacturonic acid, and highly sulfated polysaccharides, but not by GlcNAc, colominic acid, or other glycosaminoglycans. Sandwich affinity chromatography indicated that PVL can simultaneously interact with heparin- and GlcNAc-containing macromolecules. Extensive biotinylation was found to suppress the binding activity to heparin while the GlcNAc binding activity is retained. On the other hand, biotinyl PVL binds to sulfatide and the binding is not inhibited by GlcNAc, N-acetylneuraminic acid, or heparin. These results indicate that PVL is a multi-ligand adhesive lectin that can interact with various glycoconjugates. This multispecificity needs to be recognized when using PVL as a sugar-specific probe to avoid misleading information about the nature of glycoforms. (+info)