- Volume 130, Issue 10, 1984
Volume 130, Issue 10, 1984
- Physiology And Growth
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Establishment of a System Suitable for Analysis of Balanced and Unbalanced Growth of Streptomyces hygroscopicus
More LessA small-scale system was developed in which balanced growth of Streptomyces hygroscopicus occurred. Although the balanced growth, verified by corresponding increase of ATP, DNA, RNA, protein and mycelial length, was restricted to a relatively short period of the life cycle, it lasted for at least two doublings. The conditions for balanced growth could be altered by various treatments to induce imbalance. This system could be applied to study regulation in the mycelium under well-defined conditions.
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Effect of Serine Hydroxamate and Methyl α-d-glucopyranoside Treatment on Nucleoside Polyphosphate Pools, RNA and Protein Accumulation in Streptomyces hygroscopicus
More LessThe accumulation of RNA and protein and the kinetics of nucleoside triphosphate and guanosine polyphosphate pools during amino acid starvation and carbon source downshift were investigated in Streptomyces hygroscopicus. RNA accumulation was controlled stringently during both amino acid starvation and carbon source downshift. The pool size of ppGpp increased dramatically under these conditions. However, the intracellular concentrations of nucleoside triphosphates were low and the concentration of guanosine polyphosphates was much lower than in Escherichia coli. The possible significance of this phenomenon in the regulation is discussed.
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A Method for Studying cAMP-relay in Dictyostelium discoideum: the Effect of Temperature on cAMP-relay
More LessA simple assay has been developed to quantify the cAMP-relay in Dictyostelium discoideum. The assay is based on the stimulation of cells, in the presence of a phosphodiesterase inhibitor, with 2-deoxyadenosine 3′,5′-monophosphate (dcAMP) at a concentration which saturates cell surface cAMP receptors. The accumulation of cAMP is measured by an isotope dilution assay using a cAMP-binding protein with such a low affinity for dcAMP that purification of cAMP can be omitted.
The accumulation of extracellular and total cAMP was measured at 20 °C and at 0 °C. At 20 °C the rateof cAMP synthesis increased immediately after stimulation, reaching a maximum after 1 min, with a return to undetectable levels after about 4 min. The secretion of cAMP at this temperature was proportional to the intracellular cAMP concentration and reached a maximum at about 2 min. At 20 °C the cAMP-relay was essentially completed within 3·4 min, yielding about 35 pmol cAMP per 107 cells. At 0 °C the same amount of cAMP was relayed, but the rate of cAMP synthesis was reduced about 2·5-fold. The secretion rate depended on the intracellular cAMP concentration with a delay period of 1·25 ± 0·5 min, and was reduced about 5·5-fold compared to secretion at 20 °C. Due to the relatively slow secretion and fast synthesis of cAMP, an approximately twofold higher intracellular cAMP concentration was reached at 0 °C compared to 20 °C, and this persisted for about 15 min. Taking into account that the secretion rate is proportional to intracellular cAMP concentration, these results indicate that the mechanism underlying cAMP secretion is slowed 13-fold when the temperature is reduced from 20°C to 0°C.
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In vivo 13C NMR Investigations of Methanol Oxidation by the Obligate Methanotroph Methylosinus trichosporium OB3b
More LessIn vivo 13C NMR has been used to observe metabolism of exogenously supplied methanol by suspensions of Methylosinus trichosporium OB3b grown under a variety of conditions. Formaldehyde, formate and bicarbonate ions were the only metabolites of methanol to be detected. Accumulation of formaldehyde was observed only with suspensions grown under conditions which yield particulate, membrane-bound, methane mono-oxygenase (MMO). Ethyne abolished MMO activity, partially inhibited methanol oxidation in whole organisms, and prevented growth of the organism on methanol (1%, v/v) in batch culture. Oxidation of ethanol, a substrate of methanol dehydrogenase, was not affected by ethyne. Ethyne caused accumulation of formaldehyde in all suspensions of the organism incubated with methanol, although oxidation of exogenously added formaldehyde was not affected. These observations are consistent with the proposal that in M. trichosporium OB3b both MMO and methanol dehydrogenase oxidize exogenously supplied methanol and suggest that the further oxidation of formaldehyde is stimulated by the consumption of reducing equivalents by MMO.
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Translocation of Motile Cells of the Gliding Bacterium Cytophaga johnsonae Depends on a Surface Component that May Be Modified by Sugars
More LessTwenty-three sugars and sugar derivatives prevent the spread of colonies of the gliding bacterium Cytophaga johnsonae on 1·5 % agar gels. Concentrations of sugars that inhibit colony spread have no inhibitory effect on motility or growth of cells. Observations of patterns of colony spread on plates with pre-established concentration gradients of sugars indicate that cells of C. johnsonae do not exhibit a chemotactic response to compounds that inhibit their spread. Inhibitory compounds were placed into three groups based on their relative effectiveness as inhibitors. Both metabolizable and non-metabolizable sugars served as inhibitors, it was not necessary for a sugar to be transported into the cell to inhibit, and the effectiveness of a sugar as an inhibitor did not correlate with its ability to support growth. The inorganic ions Mg2●, Ca2 + and SO2− 4 also inhibit colony spread on 1·5 % agar gels. All the evidence taken together suggests that inhibitors of spread produce their effects by modifying the properties of a surface slime. The observations reported here help to give an experimental definition to two components of the gliding motility system of C. johnsonae: the motility ‘machinery’ that is responsible for an actively moving cell surface and is not affected by the presence of sugars, and an extracellular component which is sensitive to sugars and which is required for translocation of cells with moving surfaces.
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Co-ordination betweeen Elongation and Division in Escherichia coli Mediated by the wee Gene Product
More LessA procedure to construct strains of Escherichia coli containing conditional lethal mutations in two different genes was used to construct ftsA-3(ts) we(Am) supF(ts) strain. This strain, OV-25–7, was used to ascertain whether the wee gene product (Wee) acts at the level of regulation of cell elongation or at the co-ordination of elongation and division. The mass per unit length and the buoyant density of cells in the absence of Wee increased only if division was allowed, as in the case of strain OV-25 (ww(Am) supf(ls)), but not when it was inhibited, as in strain OV-25–7. These results suggested that in E. coli the wee gene product was acting at the level of coordination between elongation and cell division.
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Influence of Growth Temperature on the Development of Escherichia coli Polysaccharide K Antigens
More LessThe established seventy-one Escherichia coli polysaccharide capsular K antigenic test strains were examined for the development of the K antigen after growth at 37 °C and 18 °C. Twentyeight K antigens were not detectable after growth of bacteria at 18 °C, while the remaining 43 antigens were developed at both temperatures. Most of the temperature-dependent antigens belonged to electrophoretically fast-moving K polysaccharides of rather low molecular weight, characteristically found among the common K antigens from extraintestinal disease isolates. Lipopolysaccharide O antigens were developed at both growth temperatures.
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Arachidonic Acid and Related Molecules Affect the Behaviour of Dictyostelium discoideum Slugs
More LessAddition of micromolar concentrations of di-2-ethylhexyl phthalic acid ester (DEHP) and arachidonic acid esters to the substratum caused disorientation of phototaxis of Dictyostelium discoideum slugs similar to that observed with the as yet unidentified Slug Turning Factor (STF). The decrease in accuracy of phototaxis was dependent on the concentrations of these molecules. Several other structurally related lipid-like molecules did not affect slug phototaxis. Like STF, which affects phototaxis whether or not activated charcoal is present in the agar, arachidonic acid esters retained their activity on charcoal agar, whereas DEHP did not. Both compounds shifted the transition temperatures in slug thermotaxis away from the growth temperature. Unlike STF, they did not reduce the accuracy of positive slug thermotaxis. The data suggest that although none of these molecules can be regarded as a STF analogue, arachidonate and/or some of its metabolites may have a role in the sensory transduction in D. discoideum slugs.
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- Systematics
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Electrophoresis of Soluble Proteins from Two Species of Xenorhabdus, Bacteria Mutualistically Associated with the Nematodes Steinernema spp. and Heterohabditis spp
More LessMutualistically associated bacteria were isolated from two genera of nematodes: Xenorhabdus nematophilus from four species of Steinernema (= Neoaplectana) and X. luminescens from two species of Heterorhabditis. Mutualistic bacteria were also isolated from two unidentified species of heterorhabditid nematodes and were partially characterized by selected standard bacteriological tests. The soluble proteins obtained from the primary and secondary forms of these bacteria were subjected to electrophoretic examination on acrylamide gels. Total protein profiles and certain isoenzyme electrophoregrams were compared. The results revealed distinct subspecific differences in profiles of X. nematophilus and suggested new subspecific groupings in X. luminescens.
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Mycolic Acid Patterns of Representatives of Mycobacterium bovis BCG
More LessThe mycolic acids of 15 cultures of representative Mycobacterium bovis BCG substrains were examined by alkaline hydrolysis followed by esterification and thin-layer chromatography of the resulting methyl esters. Representatives of the Moreau and Swedish substrains had mycolic acid patterns similar to M. bovis, composed of α-mycolates, methoxymycolates and ketomycolates, but examples of the Pasteur, Glaxo, Prague, Danish and Chinese substrains did not contain methoxymycolates. This apparent subdivision of M. bovis BCG substrains is in accordance with their varying antigenic patterns recorded in other studies.
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- Short Communications
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Genetic Relationships among Cyanobacterial Strains Originally Designated as Anacystis nidulans and Some Other Synechococcus Strains
More LessDeterminations of the genetic relationships between six Synechococcus strains demonstrated that three strains, originally designated as ‘Anacystis nidulans’, belong to one and the same species. The other three strains belong to other species and/or genera. This conclusion is discussed with regard to a recently proposed revised classification of the genus Synechococcus.
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Evidence for the Presence of a Capsule in Vibrio vulnificus
More LessVibrio vulnificus strain FCC, isolated from a patient with a wound infection, and reference strain ATCC 27562, were examined by electron microscopy for the presence of capsules. Both strains had a layer heavily stained with ruthenium red. The number of stained cells was high in strain FCC and low in strain ATCC 27562. The proportion of stained cells correlated with virulence against mice and with susceptibility to the bactericidal activity of normal human serum. Rapid freezing and substitution fixation, a mild method, revealed on the cell surface a fibrous layer of relatively low electron density, which we considered to represent a capsule.
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