- Volume 81, Issue 1, 1974
Volume 81, Issue 1, 1974
- Physiology And Growth
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Localization of α-l-Arabinofuranosidase and Acid Phosphatase in Mycelium of Sclerotinia fructigena
More LessSUMMARYα-l-Arabinofuranosidase (AF) and acid p-nitrophenyl phosphatase (AP) were secreted by Sclerotinia fructigena grown in a liquid pectin/ammonium tartrate medium. ‘Gentle’ mechanical manipulation of mycelium solubilized most of the AF and much of the AP, while brief acid treatment considerably inactivated both enzymes. Both enzymes were present predominantly in a soluble form in homogenates prepared for subcellular fractionation, but some particulate activity of both was recovered from a sucrose density gradient in a fraction which also contained mitochondria. Azo-dye techniques with appropriate 1-naphthyl derivatives as substrates and p-(acetoxymercuric) aniline diazotate as capturing agent produced similar staining patterns for both enzymes in the light and electron microscopes, but the distribution of β-glycerophosphatase activity as visualized by the Gomori technique was more variable. A proportion of the activity of the enzymes remaining after fixation was located between the plasmalemma and the hyphal wall, in vacuoles in the cytoplasm, and in spherosome-like bodies. Some evidence was obtained for structure-linked latency of both enzymes and for their secretion by a process of reverse pinocytosis.
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Polyacrylamide-gel Electrophoresis of Enzymes during Morphogenesis of Sclerotia of Sclerotinia sclerotiorum
More LessSUMMARY: Succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (Glu-6-PDH) from Sclerotinia sclerotiorum (Lib.) de Bary were moderately active in submerged mycelium while in non-sclerotial aerial mycelium arylesterase and acid phosphatase were very active. In sclerotial initials, glyceraldehyde-3-phosphate dehydrogenase (Gly-3-PDH) and SDH were at their highest level of activity, Glu-6-PDH and phosphogluconate dehydrogenase (PGDH) were moderately active, laccase activity increased markedly, and tyrosinase was detected for the first time, its activity being moderate. In young compacting sclerotia, the activities of Glu-6-PDH and PGDH increased, Gly-3-PDH and SDH showed lowered activities, and laccase activity decreased. Suppression of the glycolytic Krebs-cycle pathway and the stimulation of the pentose phosphate pathway seem important during the compaction and maturation of sclerotia. Tyrosinase may be involved in sclerotial initiation.
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A Method of Isolating Anucleated Yeast Protoplasts Unable to Synthesize the Glucan Fibrillar Component of the Wall
More LessA mixture of nucleated and anucleated protoplasts was produced from log-phase Saccharomyces cerevisiae by the use of snail enzymes. The mixture was separated by centrifugation, and anucleated protoplasts were studied by means of light and electron microscopy. Anucleated protoplasts did not synthesize glucan fibrils even though they seemed to contain all other basic structures in their cytoplasm, and the structure of the plasma membrane was unchanged. This was in sharp contrast to ordinary nucleated protoplasts which synthesized glucan fibrils even after inhibition of protein synthesis by cycloheximide. The reason for this behaviour of anucleated protoplasts is not clear. Such anucleated yeast protoplasts represent the first example of uniform anucleated fungi produced by a reproducible method.
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The Action of Bacteriophage Ω8 on Two Strains of Escherichia coli 08
More LessSUMMARY: Bacteriophage Ω 8 is propagated in Escherichia coli e56b (o8: K27−: H−), a non-capsulated strain. Another non-capsulated strain, E. coli 2398 (o8:K?−:H−), is killed by bacteriophage Ω 8 without phage propagation. This strain was formerly believed to be E. coli 093:K?−:H−, cross-reacting with strain e56b. We have established chemical and serological identity of the o8-specific lipopolysaccharides of the two strains.
The o8-specific lipopolysaccharides of both strains inhibited the infection of Escherichia coli e56b with bacteriophage Ω 8 equally well. The adsorption rate constants of Ω 8 were identical for the two strains of E. coli o8. Evidence was obtained with 32P-labelled bacteriophage Ω 8 for penetration of viral DNA into both bacteria] strains. In host strain e56b, phage particle synthesis occurred normally. In strain 2398 the viral DNA was not degraded but its expression was blocked. The killing effect of D 8 on E. coli strain 2398 is supposed to be due to damage of the cytoplasmic membrane, which could not be reversed under the influence of viral information. This was indicated by a blockage of cellular respiration, β-galactoside transport and RNA as well as protein synthesis.
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Effect of Lactose on Soluble-glucan Production and on the Ultrastructure of Sclerotium rolfsii Sacc. Grown in Submerged Culture
Y. Okon, I. Chet, Naomi Kislev and Y. HenisSUMMARY
A significant increase in mycelial dry weight and a decrease in production of extracellular glucan were observed when lactose was added to a submerged culture of Sclerotium rolfsii grown in a liquid glucose-synthetic medium. When added as a sole carbon source, lactose at 2·5 % (w/v) induced the formation of dark, spherical, compact bodies. The ultrastructure of these bodies is compared with that of sclerotia formed on solid media.
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Growth of Bacillus subtilis and Spore Germination in Soil Observed by a Fluorescent-antibody Technique
More LessSUMMARY: Vegetative bacteria of Bacillus subtilis placed in contact with an acid forest soil initially declined in number but grew after the development of fungal hyphae. Growth did not occur in sterile soil, nor in alkaline forest soil unless fungal growth was stimulated. Spores of B. subtilis would not germinate in the same acid forest soil unless fungal growth took place, and hardly germinated at all in the alkaline soil. Roots of seedlings of Pinus sylvestris inhibited both vegetative growth and spore germination. These results are consistent with the observed distribution of vegetative bacteria and spores of B. subtilis in forest soils.
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- Short Communications
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Polyamine, Magnesium and Ribonucleic Acid Levels in Steady-state Cultures of the Mould Aspergillus nidulans
More LessResults from experiments in vitro strongly suggest that major roles can be ascribed to polyamines in controlling the stability, activity and synthesis of ribonucleic acids. Furthermore, functional substitution of polyamines for inorganic cations, particularly magnesium ions, in cell-free protein synthesis is well substantiated (see Cohen, 1971). Recently we have been analysing the effects of culture conditions on the chemical composition of Aspergillus nidulans and have found fluctuations in polyamine and magnesium concentrations in response to a changing environment, while biomass and RNA remained constant. This paper describes the influence of steady-state growth rate on hyphal concentrations of spermidine, spermine and Mg2+ ions.
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Alteration of Macromolecular Synthesis and Membrane Permeability by a Streptococcus sanguis Bacteriocin
More LessAlthough the elaboration of bacteriocins by streptococci has been described previously (Brock & David, 1963; Kuttner, 1966; Kelstrup & Gibbons, 1969; Overturf & Mortimer, 1970; Kramer & Brandis, 1972), few attempts have been made to purify and characterize these bactericidal factors (Kramer & Brandis, 1972). Streptococcus sanguis (strain Challis) produces a streptocin which is lethal for Streptococcus sanguis (strain Wicky) and can be purified by ammonium sulphate fractionation and Sephadex G-100 column chromatography. We exposed sensitive strain Wicky cells to Challis streptocin and observed macromolecular synthesis and membrane permeability.
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- Books Received
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