An ultrastructural analysis of protoplast–spheroplast induction in Cryptococcus neoformans

1976 ◽  
Vol 22 (10) ◽  
pp. 1518-1521 ◽  
Author(s):  
Ellena M. Peterson ◽  
Robert J. Hawley ◽  
Richard A. Calderone
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Helix Pomatia ◽  
Whole Cells ◽  
Transmission Electron ◽  
Induction Process ◽  
Entire Cell ◽  
Two Stages ◽  
Cellular Organelles

Protoplasts–spheroplasts of a human isolate of Cryptococcus neoformans were prepared using the gut enzyme of Helix pomatia. The induction process, as studied by transmission electron microscopy, occurred in two stages. Early in the induction process, protoplasts–spheroplasts emerged from whole cells through a break in the cell wall – capsule envelope. Later, a gradual dissolution of the entire cell wall occurred releasing the intact protoplast–spheroplast. A comparison of protoplasts–spheroplasts with normal untreated cells revealed that the degree of cellular vacuolation as well as the resolution of cellular organelles was similar.

scholarly journals Negative staining of whole cells: transmission electron microscopy of peripheral organelles in rat venous endothelial cells.

1978 ◽  
Vol 26 (5) ◽  
pp. 417-421
Author(s):  
D K Racker
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Simple Technique ◽  
Surface Membrane ◽  
Three Dimensional ◽  
Tubular Structures ◽  
Whole Cells ◽  
Transmission Electron ◽  
Cytoplasmic Structures ◽  
Cellular Organelles

The study of whole negatively stained cells has revealed details of cellular organelles in rat venous endothelial cells. In particular, details of surface membrane organelles and small tubular structures were demonstrated. The surface membrane organelles which appeared "vesicular-like" were found to be connected with small tubular attachments. These findings were correlated with those described by other techniques. It is significant that this simple technique appears to permit the demonstration of fine details of three-dimensional cytoplasmic structures.

The influence of acetylsalicylic acid on oxylipin migration in Cryptococcus neoformans var.neoformansUOFS Y-1378

2008 ◽  
Vol 54 (2) ◽  
pp. 91-96 ◽  
Author(s):  
Olihile M. Sebolai ◽  
Carolina H. Pohl ◽  
Piet J. Botes ◽  
Pieter W.J. van Wyk ◽  
Johan L.F. Kock
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Acetylsalicylic Acid ◽  
Cryptococcus Neoformans ◽  
Cell Walls ◽  
Bone Lesion ◽  
Acid Synthesis ◽  
Immunogold Labeling ◽  
Transmission Electron

In this paper we report the influence of acetylsalicylic acid on oxylipin migration in Cryptococcus neoformans var. neoformans UOFS Y-1378, previously isolated from human bone lesion. Transmission electron microscopy suggests that osmiophilic material originates in mitochondria and is deposited inside the yeast cell wall, from which it is excreted into the environment, along capsule protuberances, or through capsule detachments. Previous studies using immunogold labeling indicate that these osmiophilic layers contain 3-hydroxy oxylipins. In this study, the addition of acetylsalicylic acid (an inhibitor of mitochondrial function) in increasing amounts to the cells abrogated the migration of osmiophilic material, as well as capsule detachment from cell walls, and hence, oxylipin excretion. Consequently, we hypothesize that 3-hydroxy oxylipins are produced in mitochondria, probably via incomplete β-oxidation or fatty acid synthesis, from which they are deposited inside the cell wall and excreted through tubular protuberances attached to the surrounding capsules and (or) through detachment of these oxylipin-containing capsules.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques

1975 ◽  
Vol 33 ◽  
pp. 556-557
Author(s):  
M. K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Carbon Films ◽  
Photographic Recording ◽  
Transmission Electron ◽  
Thin Carbon ◽  
The Common ◽  
Scanning Electron ◽  
Better Than ◽  
Cellular Organelles

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.

scholarly journals Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 220-232 ◽  
Author(s):  
H. P. S. Abdul Khalil ◽  
M. Siti Alwani ◽  
A. K. Mohd Omar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Chemical Composition ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Anatomical Characteristics ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Palm Frond

The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.

scholarly journals Laccase Expression in Murine Pulmonary Cryptococcus neoformans Infection

2005 ◽  
Vol 73 (5) ◽  
pp. 3124-3127 ◽  
Author(s):  
Javier Garcia-Rivera ◽  
Stephanie C. Tucker ◽  
Marta Feldmesser ◽  
Peter R. Williamson ◽  
Arturo Casadevall
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Lung Tissue ◽  
Immunogold Electron Microscopy ◽  
Cell Cytoplasm ◽  
Fungal Cell ◽  
Time Of Infection

ABSTRACT Cryptococcus neoformans laccase expression during murine infection was investigated in lung tissue by immunohistochemistry and immunogold electron microscopy. Laccase was detected in the fungal cell cytoplasm, cell wall, and capsule in vivo. The amount of laccase found in different sites varied as a function of the time of infection.

Phase Contrast Enhancement with Phase Plates in Biological Electron Microscopy

2010 ◽  
Vol 18 (4) ◽  
pp. 10-13 ◽  
Author(s):  
Kuniaki Nagayama ◽  
Radostin Danev ◽  
Hideki Shigematsu ◽  
Naoki Hosogi ◽  
Yoshiyuki Fukuda ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Phase Contrast ◽  
Phase Plate ◽  
Electron Loss ◽  
Whole Cells ◽  
Transmission Electron ◽  
Different Types ◽  
Transparent Objects ◽  
Phase Plates

Theoretically, transmission electron microscopy (TEM) is compatible with three different types of phase plate: thin-film, electrostatic, and magnetic. However, designing functional phase plates has been an arduous process that has suffered from unavoidable technical obstacles such as phase-plate charging and difficulties associated with micro-fabrication of electrostatic and magnetic phase plates. This review discusses phase-contrast schemes that allow visualization of transparent objects with high contrast. Next it deals with recent studies on biological applications ranging from proteins and viruses to whole cells. Finally, future prospects for overcoming the problem of phase-plate charging and for designing the next generation of phase-plates to solve the problem of electron loss inherent in thin-film phase plates are discussed.

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.

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