scholarly journals The preparation of iodinated vancomycin and its distribution in bacteria treated with the antibiotic

1970 ◽  
Vol 116 (1) ◽  
pp. 83-92 ◽  
Author(s):  
H. R. Perkins ◽  
M. Nieto
Keyword(s):  
Cell Walls ◽  
Membrane Fraction ◽  
Living Cells ◽  
Differential Absorption ◽  
Micrococcus Lysodeikticus ◽  
Labelled Compound ◽  
Isolated Cell ◽  
Specific Peptide ◽  
Absorption Measurements

Vancomycin was radioactively labelled by iodination with 125I. Iodinated vancomycin was only a little less potent as an antibiotic than vancomycin itself. It was shown, both by chromatography and differential absorption measurements, to combine with acyl-d-alanyl-d-alanine residues. Radioactive vancomycin was used to follow the fate of the antibiotic in bacteria that had been subjected to the least concentration required to inhibit growth. Most of the radioactivity was in the cell walls, although some was found in the membrane fraction. The latter proportion increased during longer incubations with the antibiotic. Pre-formed protoplasts adsorbed very little vancomycin. Mg2+ removed labelled vancomycin from the mucopeptide of Bacillus licheniformis, but had little effect on the antibiotic adsorbed on Micrococcus lysodeikticus, either in vivo or on previously isolated cell walls. Specific peptide was shown to compete with cell walls for vancomycin and it also extracted from cell-wall samples the labelled compound that had been adsorbed on M. lysodeikticus living cells.

Coccal cell-wall compactness and the swelling action of denaturants

1972 ◽  
Vol 18 (5) ◽  
pp. 623-629 ◽  
Author(s):  
Li-Tse Ou ◽  
Robert E. Marquis
Keyword(s):  
Cell Walls ◽  
Weak Interactions ◽  
Polymer Chains ◽  
Urea Solution ◽  
Ion Exchange Resins ◽  
Low Density ◽  
Micrococcus Lysodeikticus ◽  
Exchange Resins ◽  
And Staphylococcus Aureus ◽  
Isolated Cell

Isolated cell walls of Micrococcus lysodeikticus and Staphylococcus aureus were found to have relatively low densities in both the dried and hydrated states. Thus, it appears that the component polymers of these structures do not form crystallites or other highly condensed assemblies, but rather, that their distribution within the wall matrix is similar to that of the polymer chains in low-density, ion-exchange resins. Micrococcus lysodeikticus walls, which are composed mainly of peptidoglycan, swelled significantly when they were heated or transferred to 8 M urea solution. This finding suggests that the compactness of walls and their component peptidoglycans is determined in part by weak interactions that can be disrupted by urea or by heat.

β-Glucosidase excretion in Trichoderma strains with different cell wall bound β-1,3-glucanase activities

1983 ◽  
Vol 29 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Christian P. Kubicek
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Trichoderma Viride ◽  
Culture Fluid ◽  
Exchange Chromatography ◽  
Glucosidase Activity ◽  
Different Strains ◽  
Enzyme I ◽  
Isolated Cell

Two different strains of Trichoderma pseudokoningii (SE1 A8 and SE1 D81) and Trichoderma viride QM 9123 release into the medium different proportions of the total β-glucosidase activity produced. This observation correlates with the degree of β-1,3-glucanase binding to the cell wall found for each strain. DEAE-Sephadex ion-exchange chromatography revealed three peaks of β-1,3-glucanase activity. These three enzymes (enzyme I, enzyme II, and enzyme III) differ in their extent of binding to the cell walls, their activity on isolated cell walls and Trichoderma β-glucan, and their affinity for β-glucan. Of these enzymes, enzyme II shows the largest variation in relative importance among the three strains and is located predominantly within the mural compartment. Enzyme II has the highest activity on and affinity for Trichoderma β-glucan. Enzyme II is also the most active in releasing β-glucosidase from cell walls of strain SE1 A8 (the strain excreting a high proportion of its β-glucosidase into the culture fluid) as well as from strain SE1 D81 (little β-glucosidase activity in the culture fluid). It is concluded that the action of β-1,3-glucanase II on cell wall β-glucan may be responsible for the in vivo release of cell wall bound β-glucosidase into the culture fluid.

Carbon dots derived from Fusobacterium nucleatum for intracellular determination of Fe3+ and bioimaging both in vitro and in vivo

2021 ◽  
Author(s):  
Lijuan Liu ◽  
Shengting Zhang ◽  
Xiaodan Zheng ◽  
Hongmei Li ◽  
Qi Chen ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Fusobacterium Nucleatum ◽  
Living Cells ◽  
First Time ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

Fusobacterium nucleatum has been employed for the first time to synthesize fluorescent carbon dots which could be applied for the determination of Fe3+ ions in living cells and bioimaging in vitro and in vivo with excellent biocompatibility.

scholarly journals A Role for Fas in Negative Selection of Thymocytes In Vivo

1998 ◽  
Vol 187 (9) ◽  
pp. 1427-1438 ◽  
Author(s):  
Hidehiro Kishimoto ◽  
Charles D. Surh ◽  
Jonathan Sprent
Keyword(s):  
Negative Selection ◽  
Cell Receptor ◽  
Staphylococcal Enterotoxin B ◽  
Thymic Medulla ◽  
Enterotoxin B ◽  
High Doses ◽  
Specific Peptide ◽  
Selection Of

To seek information on the role of Fas in negative selection, we examined subsets of thymocytes from normal neonatal mice versus Fas-deficient lpr/lpr mice injected with graded doses of antigen. In normal mice, injection of 1–100 μg of staphylococcal enterotoxin B (SEB) induced clonal elimination of SEB-reactive Vβ8+ cells at the level of the semi-mature population of HSAhi CD4+ 8− cells found in the thymic medulla; deletion of CD4+ 8+ cells was minimal. SEB injection also caused marked elimination of Vβ8+ HSAhi CD4+ 8− thymocytes in lpr/lpr mice. Paradoxically, however, elimination of these cells in lpr/lpr mice was induced by low-to-moderate doses of SEB (≤1 μg) but not by high doses (100 μg). Similar findings applied when T cell receptor transgenic mice were injected with specific peptide. These findings suggest that clonal elimination of semi-mature medullary T cells is Fas independent at low doses of antigen but Fas dependent at high doses. Previous reports documenting that negative selection is not obviously impaired in lpr/lpr mice could thus reflect that the antigens studied were expressed at only a low level.

Fluorescence and differential light absorption recordings with calcium probes and potential-sensitive dyes in skinned cardiac cells

1982 ◽  
Vol 60 (4) ◽  
pp. 556-567 ◽  
Author(s):  
Alexandre Fabiato
Keyword(s):  
Cardiac Cells ◽  
Arsenazo Iii ◽  
Optical Methods ◽  
Cardiac Cell ◽  
Differential Absorption ◽  
Fluorescence Measurements ◽  
Merocyanine 540 ◽  
Inverted Microscope ◽  
Optimum Wavelength ◽  
Absorption Measurements

This report describes an optical system for microspectrophotometry in a single cardiac cell from which the sarcolemma has been removed by microdissection (skinned cardiac cell). This system is attached to the high power inverted microscope used for the microdissection and includes (a) a single variable wavelength microspectrophotometer used to define the spectrum of a given dye or Ca2+ probe; and (b) a dual wavelength, differential microspectrophotometer used to record differentially between the optimum wavelength and a wavelength separated by 25–30 nm. Results are presented using the following optical methods: (a) fluorescence measurements with chlorotetracycline to monitor the amount of Ca2+ bound to the inner face of the sarcoplasmic reticulum (SR) membrane; (b) differential absorption measurements with arsenazo III to measure changes of myoplasmic [Ca2+]free resulting from Ca2+ release from the SR; (c) fluorescence and (or) differential absorption measurements with the potential-sensitive dyes merocyanine 540, NK 2367, and di-S-C3(5) to monitor changes of charge distribution on the SR membrane during Ca2+ accumulation in the SR, as well as before and during Ca2+-induced release of Ca2+ from the SR. A small and rapid signal is observed which precedes the Ca2+-induced release of Ca2+ from the SR. It is detected as an increase of Ca2+ binding inside the SR with chlorotetracycline and as a "hyperpolarization" with potential-sensitive dyes, while no transient change of myoplasmic [Ca2+]free is detected with arsenazo III. This small and rapid signal preceding the Ca2+ release may be a first hint to an understanding of the mechanism whereby a small increase of [Ca2+]free outside the SR triggers Ca2+ release from the SR.

A near-infrared fluorescence off–on probe for sensitive imaging of hydrogen polysulfides in living cells and mice in vivo

2017 ◽  
Vol 53 (62) ◽  
pp. 8759-8762 ◽  
Author(s):  
Yu Fang ◽  
Wei Chen ◽  
Wen Shi ◽  
Hongyu Li ◽  
Ming Xian ◽  
...  
Keyword(s):  
Near Infrared ◽  
Living Cells ◽  
Near Infrared Fluorescence

A new near-infrared fluorescence off–on probe with phenyl 2-(benzoylthio)benzoate as the recognition moiety is developed and applied in imaging H2Sn in living cells and mice in vivo.

Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk

2000 ◽  
Vol 67 (4) ◽  
pp. 585-596 ◽  
Author(s):  
SELVARANI GOVINDASAMY-LUCEY ◽  
PRAMOD K. GOPAL ◽  
PATRICK A. SULLIVAN ◽  
CHRISTOPHER J. PILLIDGE
Keyword(s):  
Lactococcus Lactis ◽  
Cell Walls ◽  
Cell Envelope ◽  
Laboratory Strain ◽  
Proteolytic Cleavage ◽  
Zymogram Analysis ◽  
Sds Page ◽  
Derivatives Of ◽  
Free Strains

The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 °C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology180 5947–5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined.

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