Effect of the fungicide Prochloraz-Mn on the cell wall structure of Verticillium fungicola.

The chemical structure of the cell wall of two isolates of Verticillium fungicolacollected from diseased fruit bodies of the commercial mushroom Agaricus bisporus treated with the fungicide Prochloraz-Mn was analyzed. The isolates were obtained during different periods of time and grown in the absence and presence of the LD(50) values of the fungicide for V. fungicola. In addition, another V. fungicola isolate collected previous to the routine utilization of Prochloraz-Mn but grown under the same conditions was also analyzed. The overall chemical composition of the cell wall from the three isolates showed detectable differences in their basic components, with a significant decrease in the protein content in fungicide-treated cells. This inhibitory effect was partially compensated by an increase in neutral and/or aminated carbohydrates and was accompanied by appreciable modifications of polysaccharide structure, as deduced after methylation analysis and gas-liquid chromatography-mass spectrometry (GLC-MS). Moreover, differences in hyphal morphology caused by the fungicide were observed by transmission electron microscopy (TEM).

Effect of the fungicide Prochloraz-Mn on the cell wall structure of Verticillium fungicola

The chemical structure of the cell wall of two isolates of Verticillium fungicolacollected from diseased fruit bodies of the commercial mushroom Agaricus bisporus treated with the fungicide Prochloraz-Mn was analyzed. The isolates were obtained during different periods of time and grown in the absence and presence of the LD(50) values of the fungicide for V. fungicola. In addition, another V. fungicola isolate collected previous to the routine utilization of Prochloraz-Mn but grown under the same conditions was also analyzed. The overall chemical composition of the cell wall from the three isolates showed detectable differences in their basic components, with a significant decrease in the protein content in fungicide-treated cells. This inhibitory effect was partially compensated by an increase in neutral and/or aminated carbohydrates and was accompanied by appreciable modifications of polysaccharide structure, as deduced after methylation analysis and gas-liquid chromatography-mass spectrometry (GLC-MS). Moreover, differences in hyphal morphology caused by the fungicide were observed by transmission electron microscopy (TEM) (AU)

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Chemical components and their locations in the Verticillium fungicola cell wall.

The chemical structure of cell walls and fractions of Verticillium fungicola, a pathogen of Agaricus bisporus, as well as their corresponding ultrastructures were studied. There are at least three chemically distinct types of carbohydrate polymers: one yielding mannose with lower amounts of galactose and glucose (glucogalactomannan), another one composed mainly of glucose (glucan), and a third one containing only N-acetylglucosamine (chitin). Attempts were made to locate these materials in situ by comparing electron micrographs of shadowed and sectioned cell walls, and also by indirect immunofluorescence. It was shown that none of these polymers constituted a completely physically distinct layer, but there seem to be different solubility properties in the outer, inner, and intermediate layers. It was also shown that fibrillar material (chitin) embedded in cementing glucan constituted the residual inner fraction of the original wall material. Indirect immunofluorescence showed the location of a significant amount of glucogalactomannan on the surface of the walls in which rodlet structures were visualized by electron microscopy.

News & notes: production, purification, and properties of an endo-1, 3-beta-glucanase from the basidiomycete Agaricus bisporus.

Agaricus bisporus H 25 produced extracellular endo-1, 3-beta-glucanase when grown in a static culture at 25 degrees C in a minimal synthetic medium supplemented with A. bisporus cell walls plus fructose. Endo-1,3-beta-glucanase was purified 17.85-fold from 20-day-old culture filtrates by precipitation at 80% ammonium sulfate saturation, Sephadex G-75 gel filtration, and preparative PAGE followed by electroelution. The purified enzyme yielded a single band in both native and SDS-polyacrylamide gels with a molecular mass of 32 kDa (SDS-PAGE) and 33.7 kDa (MALDI-MS), showing an isoelectric point of 3.7. The enzyme was active against beta-1,3- linkages and, to a lesser extent, against beta-1,6-, exhibiting an endohydrolytic mode of action and a glycoprotein nature. Significant activities of the endo-glucanase against laminarin and pustulan were observed between pH 4 and 5.5, and between 40 degrees and 50 degrees C for laminarin, and between 30 degrees and 50 degrees C for pustulan. The optimum pH and temperature were 4.5 and 45 degrees C for both substrates.

Enzymic activity of the mycoparasite Verticillium fungicola on Agaricus bisporus fruit body cell walls.

The in vitro production of different hydrolytic enzyme activities by Verticillium fungicola, a mycoparasite of Agaricus bisporus fruit bodies, was examined in cultures grown with various carbon sources (glucose, fructose, sucrose and A. bisporus cell walls). Several of the identified enzymes were influenced by the carbon source. The results of A. bisporus cell wall digestion by these enzymes in vitro have been compared with V. fungicola infection of A. bisporus fruit bodies in vivo. Evidence supporting mycoparasite enzymic action on the host cell walls is presented.

[Brief history of the Spanish Society of Microbiology. VI. From 1991 to 1995]. / Breve historia de la Sociedad Española de Microbiología, VI. de 1991 a 1995.

In this sixth and final chapter of the brief history of the Spanish Society for Microbiology (SEM), the major activities carried out from 1991 to 1995 are described. During that period, the 14th and 15th SEM National Congresses took place in Saragossa (1993) and Madrid (1995), respectively. The 1995 Congress was also the occasion to celebrate the fiftieth anniversary of the SEM. During that period, three new Specialized Groups were created: Molecular Microbiology. Aquatic Microbiology, and Protozoology. All Specialized Groups held their own meetings. Courses on the introduction to research in microbiology, for undergraduate students, continued, as well as the Awards of the SEM for young researchers. During that period César Nombela was elected FEMS President, and Fernando Laborda was elected President of the Biodeterioration Society. The photographs of the Presidents and Secretaries of the SEM since its foundation until 1995 are included.

New contributions to the wall polysaccharide structure of vegetative mycelium and fruit body cell walls of Agaricus bisporus.

Significant differences in chemical composition and structure of wall polysaccharides were found in Agaricus bisporus vegetative mycelium in comparison with the fruit body mycelium. Chemical fractionation of the walls demonstrated distinct percentages of the successively solubilized polysaccharides in both walls, and different proportions of their respective sugar monomers. Permethylation of isolated fractions also showed striking differences relative to the sugar linkages between the two types of walls studied. Furthermore, infrared spectrophotometry exhibited a distinct polysaccharidic configuration in several fractions. All the described differences were correlated with the transition of vegetative mycelial walls to the fruiting stage of differentiation.

Chemical and Structural Differences in Cell Wall Polysaccharides of Two Monokaryotic Strains and Their Resulting Dikaryon of Agaricus bisporus

Compatible monokaryotic strains of Agaricus bisporus ATCC 36975 and 36976 and the resulting dikaryon of their mating were grown in a liquid medium, and their respective cell walls were prepared. Significant differences were not found in the gross chemical composition of the three hyphal types. However, the neutral carbohydrate composition of the complete walls and their fractions was found to be somewhat different in each strain. More consistent differences were encountered in the chemical structure of the distinct polysaccharidic wall fractions in the three types of organisms. Some of these structural wall differences can be considered as characteristic markers for differentiating the mono- and dikaryotic types of A. bisporus.

[Brief history of the Spanish Society of Microbiology. V. From 1987 to 1991]. / Breve historia de la Sociedad Española de Microbiología, V. de 1987 a 1991.

In this fifth chapter of the short history of the Spanish Society for Microbiology (SEM), the major activities carried out from 1987 to 1991 are described. During that period, the 11th, 12th and 13th SEM National Congresses took place in Gijón (1987), Pamplona (1989) and Salamanca (1991), respectively. The Specialized Groups of the Society organized their own meetings. Courses on the introduction to research in microbiology, for undergraduate students, started in that period. The President of SEM was elected FEMS Vice-president during the Council Meeting of the Federation of European Microbiological Societies (FEMS), held in Madrid in September 1989.

[Brief history of the Spanish Society of Microbiology. III. From 1977 to 1983]. / Breve historia de la Sociedad Española de Microbiología, III. De 1977 a 1983.

This is the third article of the series about the history of the SEM. It comprises the period from 1977 to 1983. During that period, the 7th and 8th SEM national congresses took place in Cádiz (1979) and Madrid (1981) respectively, and other scientific meetings and activities of the specialized sections were organized. The executive committees of the SEM over that period are listed. SEM membership during that period increased significantly.

Two different alkali-soluble alpha-glucans in hyphal walls of the basidiomycete Armillaria mellea.

Two different polysaccharidic subfractions were separated from the alkali soluble, acid precipitated alpha-glucan located in the surface of the hyphal walls of the basidiomycete Armillaria mella. The major alpha-glucan subfraction was composed of linear chains of alpha-(1->3) and alpha-(1->4) glucan associated to protein while the less represented was mainly an alpha-(1->3) glucan with some protein. Both polysaccharidic components could correspond with the fibrillar layer in which thick fibres are longitudinally oriented and thinner fibrils cross-arranged between the others.

The structure of the mycelial wall of Agaricus bisporus.

The chemical composition of fractions extracted from the mycelial walls of Agaricus bisporus was studied. Attempts were made to locate these materials "in situ" by comparing electron micrographs of shadowed and sectioned cell walls. There are at least two chemically distinct species of carbohydrate polymers: one yielding mainly glucose with lower amounts of mannose, galactose and xylose and amino acids, and the other yielding chiefly N-acetylglucosamine with some glucose and amino acids. It was shown that none of these polymers constituted a completely physically distinct layer, but there do seem to be two regions at the outer and inner surfaces with apparently different properties. Materials which react with MnO4K to produce an electron-dense material are located throughout the wall, but tend to be concentrated in the outer and inner regions. It was shown that fibers constitute one important fraction of the original wall material.

[Importance of cellular homogenization for the posterior isolation of plasma membranes of the Candida utilis yeast]. / Importancia de la homogeneización celular en la obtención posterior de las membranas plasmáticas de la levadura Candida utilis.

Candida utilis plasma membranes were isolated from different homogenized, either whole cells or spheroplasts, by centrifugation and aggregation of mitochondrial and internal membranes at pH 4.0. As judged by electron microscopy, chemical analysis, disc electrophoresis and enzymatic assays, membrane preparations with different degrees of purity were obtained. The purest plasma membranes were those prepared by homogenization of spheroplasts in the Omnimixer Sorvall followed aggregation at mitochondrial isoelectric point as described above.

The cell walls of Agaricus bisporus and Agaricus campestris fruiting body hyphae.

The hyphal walls of Agaricus bisporus and Agaricus campestris fruiting bodies were isolated and purified. Quantitative analyses revealed that these walls consisted mainly of carbohydrates (78.3-79.2%), lipids (9.9-10.1%), and proteins (8.7-10.2%). The major components of carbohydrate polymers were glucose, N-acetylglucosamine, and glucosamine. In addition, small quantities of galactose and mannose have been found. N-Acetylglucosamine and glucosamine were identified chemically and enzymatically, and also by infrared spectrum and X-ray diffraction analyses, as chitin and chitosan. Neutral polysaccharides include an alkali-soluble glucan with alpha (1-3) linkages and a beta (1-3)- and beta (1-6)-linked glucan. The lipid fractions in both hyphal walls contained precursors of melanin, this pigment being largely represented in Agaricus spore walls. Amino acids analyses indicate that structural wall proteins were very similar in both organisms. In electron micrographs of ultrathin sections of hyphae no distinct layering was apparent in contrast with spore walls of the same organism, which show two wide well-defined layers.

Structural and immunological studies on the protoplast membrane of the yeast Candida utilis.

Cell membranes of the yeast Candida utilis isolated by lysis of protoplasts have been shown to be lipoprotein in nature. Electron microscopy shows that Mg(++) is responsible for maintaining the integrity of the membrane. A close serological relationship was found between membranes and cell walls isolated from the yeast. This relationship was exhibited not only by membranes obtained by strepzyme treatment but also by those obtained from the action of helicase enzyme. No such relationship existed between membranes and whole cells. Related data have been obtained by treatment of yeasts with different digestive enzymes. All of the results suggest that the protoplast membrane possesses traces of structural cell wall material. This material is detectable by serological tests, but not by electron microscopy.