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71.
Structural and serological characterisation of an O-specific polysaccharide from Serratia plymuthica 总被引:4,自引:0,他引:4
Abstract The surface polysaccharides of a strain of Serratia plymuthica were characterised and shown to consist of a linear, acidic galactoglucomannan as well as a major and a minor neutral galactan. Immunoblotting results demonstrated cross-reactions between this strain and others with similar galactans ( S. marcescens O16 and O20, Klebsiella O1, and Pasteurella haemolytica T4 and T10). 相似文献
72.
David J. Gower Jens B. Rasmussen Simon P. Loader Mark Wilkinson 《African Journal of Ecology》2004,42(2):83-87
A report is given of an adult caecilian, Scolecomorphus kirkii, found in the gut of a specimen of the snake Atractaspis aterrima from the Udzungwa Mountains, Tanzania. Both predator and prey are largely fossorial in soil, and their ecology is poorly known, such that this is the first reported predator of any scolecomorphid caecilian. The caecilian was ingested head first and much of the flesh from the anterior of the specimen had been digested. The prey/predator mass ratio is 0.48. This value is substantially higher than reported for A. aterrima from West Africa, and refutes the notion that this species feeds only on small prey. Most reported predators of caecilians are snakes, and a brief review is presented. 相似文献
73.
Increased cell size and shortened peptidoglycan interpeptide bridge of NaCl-stressed Staphylococcus aureus and their reversal by glycine betaine. 总被引:3,自引:0,他引:3 下载免费PDF全文
U Vijaranakul M J Nadakavukaren B L de Jonge B J Wilkinson R K Jayaswal 《Journal of bacteriology》1995,177(17):5116-5121
Staphylococcus aureus cells grown in a defined medium under conditions of high ionic stress (2.5 M NaCl) were significantly larger than cells grown under unstressed conditions, even though the cells grew much more slowly under stressed conditions. Analysis of the structure of peptidoglycan from stressed cells showed a shorter interpeptide bridge than in peptidoglycan from unstressed cells. Glycine betaine inclusion in the high-NaCl medium resulted in cells with sizes and interpeptide bridges similar to those of cells grown under unstressed conditions. 相似文献
74.
Anders Johansson Gran Widmalm Per-Erik Jansson Stephen G. Wilkinson 《Carbohydrate research》1995,270(2):191-199
The structure of the acidic polysaccharide from Serratia marcescens serogroup O1 has been investigated. NMR spectroscopy together with sugar and methylation analysis have been used as well as a uronic acid degradation. The polysaccharide consists of pentasaccharide repeating units having the following structure.
The polysaccharide also contains one equivalent of O-acetyl groups per repeating unit present on, inter alia, a hydroxymethyl group. 相似文献
75.
Development of a Robust Flow Cytometric Assay for Determining Numbers of Viable Bacteria 总被引:9,自引:3,他引:6 下载免费PDF全文
R. I. Jepras J. Carter S. C. Pearson F. E. Paul M. J. Wilkinson 《Applied microbiology》1995,61(7):2696-2701
Several fluorescent probes were evaluated as indicators of bacterial viability by flow cytometry. The probes monitor a number of biological factors that are altered during loss of viability. The factors include alterations in membrane permeability, monitored by using fluorogenic substrates and fluorescent intercalating dyes such as propidium iodide, and changes in membrane potential, monitored by using fluorescent cationic and anionic potential-sensitive probes. Of the fluorescent reagents examined, the fluorescent anionic membrane potential probe bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC(inf4)(3)] proved the best candidate for use as a general robust viability marker and is a promising choice for use in high-throughput assays. With this probe, live and dead cells within a population can be identified and counted 10 min after sampling. There was a close correlation between viable counts determined by flow cytometry and by standard CFU assays for samples of untreated cells. The results indicate that flow cytometry is a sensitive analytical technique that can rapidly monitor physiological changes of individual microorganisms as a result of external perturbations. The membrane potential probe DiBAC(inf4)(3) provided a robust flow cytometric indicator for bacterial cell viability. 相似文献
76.
H. W. Wilkinson 《The Yale journal of biology and medicine》1984,57(4):567-572
Standardized serologic tests for Lyme disease are needed, as isolation or in situ demonstration of the spirochete has proved difficult. At the Centers for Disease Control (CDC), an indirect immunofluorescence assay (IFA) was modified from a previously described IFA, and an enzyme-linked immunosorbent assay (ELISA) was developed with soluble spirochetal antigens. Both tests were evaluated with sera from Lyme disease patients, normal controls, and patients with other diseases. They were highly specific for Lyme disease when sera from patients with syphilis were excluded. Sensitivity varied with disease stage: for patients with erythema chronicum migrans alone, the IFA was 53 percent sensitive and the ELISA was 67 percent sensitive. In contrast, all patients with complicated Lyme disease had at least one serum specimen positive in both tests. Twenty-six percent of the sera from 289 patients with suspected Lyme disease that were submitted to CDC in 1983 had IFA titers greater than or equal to 256 and thus were considered positive. Both tests should be useful diagnostic and epidemiologic aids. 相似文献
77.
A retrospective study of 20 patients who underwent vena caval fenestration showed that in 50% of the patients the procedure was done for prophylaxis and in 50% it was done for therapeutic reasons. After this procedure five patients had persistent leg swelling, two had deep venous thrombosis, two had pulmonary emboli and one died of a respiratory arrest. We recommend limiting the use of vena caval fenestration to those patients who have verified pulmonary embolism while adequately anticoagulated or patients who have pulmonary embolism and a major contraindication to anticoagulation. 相似文献
78.
Analyses have been carried out on lipopolysaccharides (LPS) from 14 strains of Enterobacter cloacae representing different O serotypes. All of the products appeared to have a composition and architecture typical of enterobacterial LPS, but points of interest include the absence of phosphate residues from the core oligosaccharide, the presence of both L-glycero-D-mannoheptose and D-glycero-D-mannoheptose (ratio usually about 4:1), and the presence in lipid A of small amounts of fatty acids with odd numbers of carbon atoms (mainly C13) in addition to tetradecanoic acid and 3-hydroxytetradecanoic acid. Monosaccharides identified as components of polymeric fractions from the LPS were glucose, galactose, mannose, rhamnose, glucosamine, galactosamine, fucosamine, and galacturonic acid. Most polymeric fractions also probably contained an O-acetyl substituent. Closely similar chemotypes found for the polymeric fractions from the LPS of cross-reacting serotypes support the view that these fractions contain the O-antigenic determinants and represent the side chains of the LPS. 相似文献
79.
Summary The binding to neutrophil leukocytes of human serum albumin (HSA), which is chemokinetic for leukocytes, i.e. influences their rate of locomotion, and of alkali-denatured HSA, which is chemotactic for leukocytes, i.e. influences their direction of locomotion, was studied. Native serum albumin showed low affinity binding to the neutrophil surface. Denatured serum albumin showed saturable binding with a Ka of approximately 106 litres per mole to about 106 binding sites per cell. Another protein chemotactic factor, s-casein, gave similar binding. These results exclude that chemotactic reactions to denatured proteins are mediated in a completely non-specific manner and suggest the presence on the cell of a restricted number of defined recognition sites. Binding was reduced following treatment of the cells with either of two lipid-specific bacterial toxins, perfringolysin, the -toxin of Clostridium perfringens, an oxygen-labile cholesterol-specific toxin, and Staphylococcus aureus Sphingomyelinase C. Both have previously been shown to reduce chemotactic reactions and both were used at doses which did not reduce cell viability. These results suggest an important, and possibly direct, role for membrane lipid in the binding sites for chemotactic factors. Visual analysis of the behaviour of perfringolysin-treated neutrophils showed that these cells were still capable of chemotactic locomotion. The cells appeared to be less efficient than normal in detecting chemotactic gradients only when at a distance from the gradient source, a finding which is consistent with reduced binding of the chemotactic factor to the cell surface. 相似文献
80.
Isolation and characterization of isocitrate lyase from a thermophilic Bacillus sp. 总被引:6,自引:1,他引:5 下载免费PDF全文
Isocitrate lyase was isolated in homogeneous state from a thermophilic Bacillus. The enzyme has a mol.wt. of 180000 and a pI of 4.5 and contains threonine as the N-terminal residue. It resembles in size the cognate enzyme from the mesophilic bacterium Pseudomonas indigofera, but is smaller than the enzyme from the eukaryotic fungus Neurospora crassa. All three lyases are tetramers and similar in amino acid composition, but the thermophile enzyme is distinctive from its mesophilic coutnerparts in possessing a lower catalytic-centre activity, greater resistance to chemical and thermal denaturation and fewer thiol groups and in being strongly activated by salts. Salt activation, by 0.4M-KCl, is about 3-fold at 30 degrees C and pH 6.8 and weakens progressively as the temperature or pH is raised. The activation is probably due to a change in the enzyme conformation caused by the electrolyte modifying the interaction between charged groups or between hydrophobic groups in protein. The possible significance of the salt activation, of the relative paucity of thiol groups and of the greater resistance to chemical denaturants is discussed. Besides its effect on the Vmax., KCl produces large increases in the magnitude of several kinetic parameters. A rise in reaction temperature from 30 to 55 degrees C produces a somewhat similar result. In view of these peculiar features, the patterns of inhibition of enzyme activity by compounds such as succinate and phosphoenolpyruvate were examined at 30 and 55 degrees C in the presence and absence of KCl. 相似文献