Spheroplasts of Lactobacillus Casei and the Cellular Distribution of Bactoprenol

1970 ◽  
Vol 7 (3) ◽  
pp. 755-785
Author(s):  
D. C. BARKER ◽  
KAREEN J. I. THORNE
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Lactobacillus Casei ◽  
Mevalonic Acid ◽  
Simultaneous Action ◽  
Cell Wall Biosynthesis ◽  
Cellular Distribution ◽  
Hypotonic Medium ◽  
Weak Point ◽  
Thin Sections

Spheroplasts of L. casei were prepared by the simultaneous action of trypsin and lysozyme in the presence of EDTA and 20% sucrose. Electron microscopy of thin sections of cells during the formation of spheroplasts showed that the spheroplasts emerged from the cell wall through a weak point at one end of the cell. Electron microscopy of negatively stained preparations showed that the structure of spheroplast membranes obtained by disruption in hypotonic medium varied according to the nature of the hypotonic medium used. Disruption in water gave small, delicate membrane fragments; disruption in 0.1 M tris-Cl gave large pieces with tubulo-vesicular attachments. The effects of Mg2+ and EDTA were also investigated. Bactoprenol, the C55 isoprenoid alcohol concerned in cell wall biosynthesis, was located by growing L. casei in [14C]mevalonic acid. Over 90% of the cellular bactoprenol was found in the spheroplast membrane when this was obtained with 0.1 M tris-Cl, but only 42% when the spheroplasts were burst in water. It is suggested that the missing bactoprenol may be solubilized with the membranes of mesosomal orgin, and that bactoprenol is therefore a component of both plasma and mesosomal membranes.

scholarly journals Human β-Defensin 3 Inhibits Cell Wall Biosynthesis in Staphylococci

2010 ◽  
Vol 78 (6) ◽  
pp. 2793-2800 ◽  
Author(s):  
Vera Sass ◽  
Tanja Schneider ◽  
Miriam Wilmes ◽  
Christian Körner ◽  
Alessandro Tossi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Host Defense ◽  
Transcriptional Response ◽  
Cell Wall Biosynthesis ◽  
Host Defense Peptides ◽  
Lipid Ii ◽  
Transmission Electron ◽  
Host Defense Peptide

ABSTRACT Human β-defensin 3 (hBD3) is a highly charged (+11) cationic host defense peptide, produced by epithelial cells and neutrophils. hBD3 retains antimicrobial activity against a broad range of pathogens, including multiresistant Staphylococcus aureus, even under high-salt conditions. Whereas antimicrobial host defense peptides are assumed to act by permeabilizing cell membranes, the transcriptional response pattern of hBD3-treated staphylococcal cells resembled that of vancomycin-treated cells (V. Sass, U. Pag, A. Tossi, G. Bierbaum, and H. G. Sahl, Int. J. Med. Microbiol. 298:619-633, 2008) and suggested that inhibition of cell wall biosynthesis is a major component of the killing process. hBD3-treated cells, inspected by transmission electron microscopy, showed localized protrusions of cytoplasmic contents, and analysis of the intracellular pool of nucleotide-activated cell wall precursors demonstrated accumulation of the final soluble precursor, UDP-MurNAc-pentapeptide. Accumulation is typically induced by antibiotics that inhibit membrane-bound steps of cell wall biosynthesis and also demonstrates that hBD3 does not impair the biosynthetic capacity of cells and does not cause gross leakage of small cytoplasmic compounds. In in vitro assays of individual membrane-associated cell wall biosynthesis reactions (MraY, MurG, FemX, and penicillin-binding protein 2 [PBP2]), hBD3 inhibited those enzymes which use the bactoprenol-bound cell wall building block lipid II as a substrate; quantitative analysis suggested that hBD3 may stoichiometrically bind to lipid II. We report that binding of hBD3 to defined, lipid II-rich sites of cell wall biosynthesis may lead to perturbation of the biosynthesis machinery, resulting in localized lesions in the cell wall as demonstrated by electron microscopy. The lesions may then allow for osmotic rupture of cells when defensins are tested under low-salt conditions.

ELECTRON MICROSCOPY OF ULTRATHIN SECTIONS OF MICROCOCCUS CRYOPHILUS

1966 ◽  
Vol 12 (3) ◽  
pp. 465-469 ◽  
Author(s):  
K. Mazanec ◽  
M. Kocur ◽  
T. Martinec
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Micrococcus Luteus ◽  
Nuclear Material ◽  
Granular Structure ◽  
Condensed Chromatin ◽  
Thin Sections ◽  
Ultrathin Sections

Ultra thin sections of Micrococcus cryophilus cells were investigated. The cell wall, consisting of several layers, measures 410–500 Å and is covered with a distinct capsule. The cytoplasm, which is of granular structure, includes ribosomes, condensed chromatin, and occasionally mesosomes. The nuclear material has various shapes and is formed by filaments proceeding in various directions. We could find no evidence to bear out the supposition of Kocur and Martinec (1962) that M. cryophilus is related to Micrococcus luteus. M. cryophilus is, in its structure as well as its groupings of cells, different from micrococci, which leads us to believe that it does not belong to the genus Micrococcus.

scholarly journals THE COMPOSITION AND STRUCTURE OF BACTERIAL SPORES

1963 ◽  
Vol 16 (3) ◽  
pp. 579-592 ◽  
Author(s):  
A. D. Warth ◽  
D. F. Ohye ◽  
W. G. Murrell
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Heat Resistance ◽  
Dipicolinic Acid ◽  
Diaminopimelic Acid ◽  
Bacterial Spores ◽  
Bacillus Species ◽  
Thin Sections ◽  
Composition And Structure ◽  
Soluble Fractions

The composition of the insoluble "integuments" and soluble "contents" fractions of spores of four Bacillus species of widely differing heat resistance were compared. Electron microscopy of thin sections was also used to determine and compare the morphological structures in the integument preparations. The soluble fractions of the thermophiles, B. coagulans and B. stearothermophilus, had a higher content of hexose and dipicolinic acid. The hexose content of both fractions of the four species was related to heat resistance. Integument fractions consisted chiefly of protein together with variable amounts of the mucopeptide constituents, α, ϵ-diaminopimelic acid (DAP) and hexosamine. In the thermophiles the DAP and hexosamine were found chiefly in the insoluble integuments fractions, while in B. cereus and B. subtilis most of this material was soluble. Integument preparations, containing mainly protein with little mucopeptide, consisted chiefly of outer and inner spore coats, while preparations having more mucopeptide contained also residual cortical material and a cortical membrane (possibly the germ cell wall). The results suggest that spore integuments consist of mainly proteinaceous outer and inner coats together with variable amounts of residual cortex and cortical membrane which contain the mucopeptide material.

Dimorphism of Penicillium marneffei as observed by electron microscopy

1973 ◽  
Vol 19 (10) ◽  
pp. 1305-1309 ◽  
Author(s):  
Robert G. Garrison ◽  
Karen S. Boyd
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Penicillium Marneffei ◽  
Lipid Bodies ◽  
Hyphal Cell ◽  
Dimorphic Fungi ◽  
Thin Sections ◽  
Internal Morphology ◽  
Tissue Phase ◽  
Altered Lipid

Aspects of the culturally induced mycelial- to tissue-phase transformation of Penicillium marneffei were studied by electron microscopy of thin sections. The hyphal cell was observed to contain multiple, large lipid bodies scattered throughout the cytoplasm. Five days after induction of conversion, short elements arose which were characterized by the presence of two polar areas of vacuolation containing electron-opaque material thought to be altered lipid. This material could not be demonstrated with permanganate fixation, but reacted strongly with thiocarbohydrazide. The latter reagent is known to enhance the electron density of osmium-stained lipids. After 10 days incubation, the tissue-phase cells appeared to be slightly elongate with one or more septa present as the result of division by fission. The cell wall appeared to be of uniform electron opacity with a slightly roughened appearance to the outer surface. Except for residuals of polar vacuolation, the internal morphology of the tissue phase of P. marneffei appeared similar in many respects to that of the analogous yeast-like phases of certain other of the pathogenic dimorphic fungi.

Fine structure of Arthrobacter crystallopoietes during long-term starvation of rod and spherical stage cells

1973 ◽  
Vol 19 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Charles W. Boylen ◽  
Jack L. Pate
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Fine Structure ◽  
Cell Size ◽  
Morphological Changes ◽  
Thin Sections ◽  
Size And Shape ◽  
Arthrobacter Crystallopoietes ◽  
Total Starvation

Actively growing spherical and rod-shaped cells of Arthrobacter crystallopoietes were subjected to total starvation in buffer for 8 weeks. At intervals, thin sections of cells were prepared and examined by electron microscopy. Starving cells underwent no morphological changes that would account for their unusual survival capabilities. Cell size and shape remained unaltered. There was no thickening of the cell wall and no development of structures similar to those observed in spores or cysts. As the length of starvation increased, the following changes were observed; glycogen deposits disappeared, the number of ribosome particles decreased, the number of vesicular membranes increased within the cell, and the nucleoplasm expanded in volume to fill the emptying cytoplasm.

Morphological and cytological effects of carbenicillin on Pseudomonas pseudomallei

1974 ◽  
Vol 20 (9) ◽  
pp. 1229-1233
Author(s):  
Carole R. Dilworth ◽  
Mervyn Franklin ◽  
Gerald N. Bance
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Protein Synthesis ◽  
Cell Walls ◽  
Inclusion Bodies ◽  
Exponential Phase ◽  
Filament Formation ◽  
Early Exponential Phase ◽  
Thin Sections ◽  
Pseudomonas Pseudomallei

Microscopic observation of P. pseudomallei revealed that impaired cell division occurred upon the addition of carbenicillin to early exponential phase cultures. Cells were noticeably elongated after 1 h, and continued to increase in length with time. At 6 h filaments were abundant. Spherical bodies, some of which appeared to lyse, were frequently observed along the length of these filaments. Electron microscopy of thin sections confirmed that filament formation proceeded without fission, and constrictions were absent. Replication and segregation of DNA appeared normal; and the density of ribosomes suggested that protein synthesis was not impaired. Two types of inclusion bodies, observed in the nucleoid region of the filaments, were more pronounced compared with untreated cells. It was speculated that one of the inclusions was polyphosphate. The cell walls of the filaments showed decreased electron density. These observations suggest that synthesis of components of the cell wall is impaired by carbenicillin.

scholarly journals THE FINE STRUCTURE AND MODE OF ATTACHMENT OF THE SHEATHED FLAGELLUM OF VIBRIO METCHNIKOVII

1963 ◽  
Vol 18 (2) ◽  
pp. 327-336 ◽  
Author(s):  
Audrey M. Glauert ◽  
D. Kerridge ◽  
R. W. Horne
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Thin Sections ◽  
Basal Disc ◽  
The Core ◽  
Thin Sectioning ◽  
Potassium Phosphotungstate ◽  
Mode Of Attachment

The sheathed flagellum of Vibrio metchnikovii was chosen for a study of the attachment of the flagellum to the bacterial cell. Normal and autolysed organisms and isolated flagella were studied by electron microscopy using the techniques of thin sectioning and negative staining. The sheath of the flagellum has the same layered structure as the cell wall of the bacterium, and in favourable thin sections it appears that the sheath is a continuation of the cell wall. After autolysis the sheath is usually absent and the core of the flagellum has a diameter of 120 A. Electron micrographs of autolysed bacteria negatively stained with potassium phosphotungstate show that the core ends in a basal disc just inside the plasma membrane. The basal disc is about 350 A in diameter and is thus considerably smaller than the "basal granules" described previously by other workers.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Lead aspartate: a new en bloc stain for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 34-35
Author(s):  
J.R. Walton
Keyword(s):  
Electron Microscopy ◽  
Calcium Ion ◽  
Enzyme Reaction ◽  
Lead Citrate ◽  
Reaction Products ◽  
En Bloc ◽  
Thin Sections ◽  
Lead Salts ◽  
Thin Sectioning ◽  
High Alkalinity

In electron microscopy, lead is the metal most widely used for enhancing specimen contrast. Lead citrate requires a pH of 12 to stain thin sections of epoxy-embedded material rapidly and intensively. However, this high alkalinity tends to leach out enzyme reaction products, making lead citrate unsuitable for many cytochemical studies. Substitution of the chelator aspartate for citrate allows staining to be carried out at pH 6 or 7 without apparent effect on cytochemical products. Moreover, due to the low, controlled level of free lead ions, contamination-free staining can be carried out en bloc, prior to dehydration and embedding. En bloc use of lead aspartate permits the grid-staining step to be bypassed, allowing samples to be examined immediately after thin-sectioning.Procedures. To prevent precipitation of lead salts, double- or glass-distilled H20 used in the stain and rinses should be boiled to drive off carbon dioxide and glassware should be carefully rinsed to remove any persisting traces of calcium ion.

Sign in / Sign up

Export Citation Format

Share Document