- Volume 134, Issue 5, 1988
Volume 134, Issue 5, 1988
- Pathogenicity And Medical Microbiology
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Antibodies to the C Epitope of Neisseria gonorrhoeae Are Present in Patients with Gonorrhoea and Absent in Normal Sera
More LessWe have previously described a surface oligosaccharide antigen (epitope C) present in fresh isolates of Neisseria gonorrhoeae and in variants grown in subcutaneous chambers, but poorly formed by variants repeatedly subcultured in vitro. We have now investigated the presence of antibodies to epitope C in sera from normal individuals and from patients with gonorrhoea. Sera were analysed by Western blotting and ELISA, and compared with a pool of sera from normal individuals with no known history of gonorrhoea. Antigenic extracts and monoclonal antibody to the C epitope were used for competition and inhibition studies. Only the sera from patients contained antibodies to epitope C. Antibodies to several other gonococcal antigens were found in sera from patients, and also in normal sera. Collectively, the results indicate that epitope C is expressed in humans, that patients with gonorrhoea develop antibodies to it, and that such antibodies are absent in sera of normal individuals.
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Adherence of Streptococci to Surface-modified Glass
N. Satou, J. Satou, H. Shintani and K. OkudaFour types of surface-modified glass were prepared. Aminopropyl glass was prepared by alkylsilylation of glass slides with ?-aminopropyltriethoxysilane. This glass carries primary amino groups which may be protonated at pH 7.2. Owing to the presence of both positively charged ions and hydrophobic ethoxyl groups, the glass is considered to be amphipathic. Three other types of surface-modified glass slides were prepared from aminopropyl glass by forming Schiff's bases with three aldehydes: glucose, glyoxylic acid and hexanal. The aldehyde-treated slides were subsequently reduced using sodium borohydride. Thus, the surface of the glass was rendered hydrophilic, ampholytic or hydrophobic, respectively. The adherence of two Streptococcus sanguis strains and two Streptococcus mutans strains to the surface-modified glass slides was studied. Different strains showed differences in adherence to these slides depending on their physico-chemical surface properties. For S. sanguis ATCC 10556, hydrophobic bonds seemed to be most important, while in S. mutans OMZ 176, ionic interactions made the highest contribution to adhesion. Hydrogen bonds seemed to contribute least to adherence.
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Attachment of Mycobacteria to Fibronectin-coated Surfaces
This report investigates the extent of the expression of fibronectin (FN) binding properties among the mycobacteria and provides preliminary characteristics of the bacterial molecule(s) mediating attachment. Eight BCG substrains, three Mycobacterium tuberculosis strains and four other mycobacterial species all expressed FN-binding capacity. Treatment of organisms with detergent prior to the binding assay destroyed the FN-binding capacity of BCG but not that of Staphylococcus aureus. Trypsin pretreatment eliminated the FN-binding capacity of both BCG and S. aureus. [35S]Methionine-labelled material in supernatants from BCG and M. tuberculosis cultures attached to FN-coated surfaces. These culture supernatants inhibited the attachment of BCG but not S. aureus to FN-coated surfaces. This inhibitory activity of the supernatants was removed by affinity chromatography on FN-Sepharose but was not affected by similar passage over a control column (human serum albumin attached to Sepharose). These results demonstrate that the ability to bind FN is present in all mycobacterial species tested and suggest that attachment is mediated by trypsin-sensitive cell-surface component(s).
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HEp-2 Adhesion and the Expression of a 94 kDa Outer-membrane Protein by Strains of Escherichia coli Belonging to Enteropathogenic Serogroups
More LessSixty strains of Escherichia coli belonging to enteropathogenic serogroups (EPEC) were examined for the ability to adhere to HEp-2 cells, the possession of the genes encoding EPEC adherence factor (EAF) and the ability to express an outer-membrane protein (OMP) of 94 kDa thought to be involved in bacterial adhesion to eukaryotic cells. An absolute correlation was found between HEp-2 adhesion and the possession of the genes encoding EAF. An OMP of 94 kDa was observed in the SDS-PAGE profile of most adhesive strains. In some strains this protein was prone to proteolytic degradation. An antiserum raised to a HEp-2 adhesive strain of EPEC did not react with the 94 kDa OMP of all EPEC which were EAF-positive and HEp-2 adhesive, indicating some interstrain antigenic variation of this protein. Although this 94 kDa protein was surface-exposed, specific antibodies binding to the 94 kDa protein in situ in the outer membrane did not interfere with adhesion of EPEC to HEp-2 cells. Therefore, these studies question the value of this protein as a potential vaccine component.
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- Physiology And Growth
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Cytoplasmic Alkalinization during Germ Tube Formation in Candida albicans
More LessWeak acids were used to measure the internal pH of yeast cells of Candida albicans that had been induced to form buds or germ tubes. Under conditions that supported germ tube formation the internal pH rose from around 6·8 to over 8·0 after 30 min in two different induction media. Internal pH measured by 31P NMR confirmed this pattern and also showed that the internal pH fell to around 7·0 prior to the outgrowth of germ tubes. Conditions which led to budding induced less cytoplasmic alkalinization. This alkalinization was brought about when cells were inoculated into media of neutral pH and at an increased temperature. Increasing the temperature of the medium augmented the alkalinization of the cytoplasm induced by raising the external pH. Strains of C. albicans defective in the ability to produce germ tubes did not show this dramatic cytoplasmic alkalinization under conditions which normally supported filamentous growth. The raising of internal pH may be due to the activation of the plasma membrane proton-pumping ATPase since diethylstilboestrol inhibited the cytoplasmic alkalinization and germ tube formation without causing irreversible loss of cell viability. The results show that the induction of the dimorphic transition in this organism is accompanied by a steep rise in internal pH. It is not known whether these changes are the cause or consequence of morphogenesis.
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Transcellular Ion Currents during Sporangium Development in the Water Mould Achlya bisexualis
More LessChanges in the pattern of electric currents that accompany the transformation of growing hyphae of Achlya bisexualis into sporangia have been examined. When hyphae were transferred to a non-nutrient buffer, they continued to extend for several hours and then gave rise to sporangia. Throughout this process, current (positive charge) flowed into the apical region that corresponds approximately to the future sporangium. The current ceased after the crosswall appeared. The sporangium then remained electrically quiescent, except for a brief intense burst of outward current at the homogeneous stage of spore cleavage. The inward current during sporangium formation largely represents an influx of protons. Addition of nitrate abolished the flow of electric current with little effect on sporulation. The late burst of outward current is most probably an artefact, generated by the discharge of salts from the sporangial vacuole. The transcellular electric current apparently plays no role in sporangium formation or in spore cleavage. Calcium ions, however, are required and may traverse the plasma membrane.
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The Utilization of Pyridine Carbonitriles and Carboxamides by Nocardia rhodochrous LL100-21
More LessNocardia rhodochrous LL100-21 utilized 2-, 3- or 4-cyanopyridine (2-, 3- or 4-pyridine carbonitrile) and the corresponding pyridine carboxamides as sources of nitrogen for growth. Studies with intact bacteria and cell-free extracts indicated that 3-cyanopyridine was hydrolysed directly to nicotinic acid by an inducible 3-cyanopyridinase enzyme (a nitrilase), and that the organism also possessed a separately inducible nicotinamidase. In cultures supplied with 3-cyanopyridine or nicotinamide as the source of nitrogen the compounds were hydrolysed to form ammonia, which was utilized for growth, and nicotinic acid, which was not further metabolized and accumulated in the culture medium. In cultures containing 3-cyanopyridine, which had a bacteriostatic effect, little growth occurred until all the nitrile had been converted to nicotinic acid; the specific activity of 3-cyanopyridinase of the bacteria was highest in the early exponential phase of growth and had disappeared by the stationary phase. Measurements of the abilities to either oxidize or release ammonia from heterocyclic, aromatic and aliphatic nitriles and amides by bacteria grown on the various substrates indicated that benzonitrile acted as both a substrate and an inducer of 3-cyanopyridinase activity, whereas benzamide acted as a substrate and an inducer of nicotinamidase. These enzymes are induced separately from the acetonitrile hydratase/acetamidase enzyme system of this bacterium.
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Adaptation of the Kinetics of Glucose Transport to Environmental Conditions in the Yeast Candida utilis CBS 621: a Continuous-culture Study
More LessThe relation between the kinetic parameters of glucose transport and the physiology of Candida utilis CBS 621 was studied in chemostat cultures. In glucose-limited cultures the transport parameters were dependent on the growth rate of the yeast. Three different transport systems were found which differed by an order of magnitude in their affinity constants, namely a high-affinity (K m 25 µm), a medium-affinity (K m 190 µm), and a low-affinity uptake system (K m 2000 µm). Cells growing at a dilution rate of 0.45 h-1 or less had the high- and medium-affinity uptake systems. At a dilution rate of 0·52 h−1 the high-affinity system was absent and both the medium-and low-affinity systems were present. At a dilution rate close to µ max (0·57 h−1) only the low-affinity system was detected. The in situ contribution of each of the transport systems to glucose consumption in glucose-limited cultures was estimated on the basis of their kinetic parameters (K m and V max) and the residual glucose concentration in these cultures. The sum of the calculated rates of transport corresponded to the in situ rate of glucose consumption by the cultures as determined from the yield constant and the dilution rate. The dependence of the transport parameters on the growth rate and hence on the environmental sugar concentration was also evident in cells grown under nitrogen limitation. In contrast to carbon-limited cells, nitrogen-limited cultures growing at D = 0·15 h−1 did not exhibit the high-affinity glucose uptake system, whereas the medium- and low-affinity systems were present.
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Glutathione Formation in Penicillium chrysogenum: Stimulatory Effect of Ammonium
More LessPenicillium chrysogenum produced glutathione after growth in a defined medium containing 10mm-NH4Cl as the sole source of nitrogen. The use of higher ammonium concentrations (100 mm) resulted in stimulation of growth and glutathione formation. In addition, increases in the intracellular pools of glutamate, alanine and glutamine, proportional to the amount of ammonium present in the medium were observed. Resting cell systems, prepared from cells previously grown with ammonium, were able to produce glutathione when incubated with ammonium or the amino acids glutamate, alanine and glutamine. A mutant lacking NADP-dependent glutamate dehydrogenase activity (which has a leaky phenotype on ammonium as sole nitrogen source) required glutamate to synthesize glutathione. Resting cell systems of this mutant, prepared from cells previously grown with ammonium, did not produce glutathione even when incubated with glutamate or glutamine. On the other hand, resting cell systems of this mutant produced glutathione if prepared from cells previously grown with glutamate. The addition of glutamate to resting cell systems of the wild-type strain stimulated the synthesis of γ-glutamylcysteine synthetase, the first enzyme of glutathione biosynthesis.
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Ethanol Tolerance and the Induction of Stress Proteins by Ethanol in Candida albicans
More LessEthanol is one of the products of the metabolism of glucose by Candida albicans. The amount produced is directly related to the concentration of glucose in the medium. The fungus utilizes ethanol as a sole source of carbon but is relatively intolerant of ethanol in its environment. Ethanol induces germ tube formation by blastoconidia of C. albicans. Germination was not seen under fermentation conditions even though the amount of ethanol produced was in the range that induced germ tubes when added to phosphate buffer. Ethanol also induces C. albicans to form stress proteins that are similar to heat shock proteins. The possibility that stress proteins may regulate germ tube formation by C. albicans is discussed.
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Purification, Some Properties and Possible Physiological Role of an Extracellular Cobalamin Binding Protein from Euglena gracilis
More LessThe extracellular cobalamin (Cbl) binding protein from Euglena gracilis was purified and some properties of the protein were studied for the elucidation of its physiological role. The protein was purified about 20-fold with a yield of 15% and was homogeneous on PAGE. SDS-PAGE indicated that the protein had a single type of polypeptide of M r 56000. The protein could bind some Cbl analogues with different β-coordination moieties, over a wide range of pH values from 4·0 to 9·0, and the K s value for cyanocobalamin was 1·1 nm. The extracellular Cbl binding protein was located on the cell surface of E. gracilis, probably bound in the muciferous layer.
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- Systematics
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Taxonomic Studies on Brochothrix, Erysipelothrix, Listeria and Atypical Lactobacilli
More LessOne hundred and eighty-seven strains of listeriae, atypical lactobacilli, Brochothrix, Erysipelothrix and related Gram-positive bacteria were tested for 140 characters based on morphology, physiology and biochemistry. Computer analyses of the data resulted in the recovery of 20 phenons. Representative strains were examined for cytochrome content, cell wall, fatty acid and isoprenoid quinone composition and the G + C content of the DNA. The results indicate that the species Listeria monocytogenes, L. innocua and L. ivanovii are phenotypically very similar. L. grayi and L. murrayi are more distinct from these but are so similar to each other that L. murrayi should be regarded as a subspecies of L. grayi. Some of the atypical lactobacilli studied are members of the genus Brochothrix; the others probably represent four distinct species in a new genus.
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DNA Probes with Different Specificities from a Cloned 23S rRNA Gene of Micrococcus luteus
More LessA 7500 bp PstI restriction fragment of chromosomal DNA from Micrococcus luteus containing a 23S rRNA gene was cloned in vector pHE3 in E. coli RR 28 (the recombinant plasmid was designated pAR1). A recombinant phage (pAR5) hybridizing to all eubacteria tested was constructed by shotgun subcloning of the PstI fragment in phage M13mp8. Further subcloning of the fragments of the 23S rRNA gene in the vectors pTZ18R and pTZ19R using selected restriction sites of the gene enabled us to select cloned fragments of the 23S rRNA gene representing different specificities. Probes specific for Micrococcus luteus-Micrococcus lylae (pAR28), for the Arthrobacter-Micrococcus group (pAR27), for eubacteria (pAR5), and for the detection of eu- and archaebacteria (the so-called universal probe pAR17) were constructed. The specificity of each probe was analysed by dot hybridization to the chromosomal DNAs of representatives of most of the main phyla of eu- and archaebacteria.
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- Corrigenda
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Volumes and issues
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Volume 170 (2024)
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