scholarly journals Chloramphenicol-Related Changes in Mitochondrial Ultrastructure

1970 ◽  
Vol 7 (2) ◽  
pp. 501-521
Author(s):  
UNA SMITH ◽  
D. S. SMITH ◽  
ADEL. A. YUNIS
Keyword(s):  
Oxidative Phosphorylation ◽  
Insect Flight ◽  
Potent Inhibitor ◽  
Mitochondrial Protein ◽  
Electron Microscopic Examination ◽  
Excellent Correlation ◽  
Ideal Model ◽  
Electron Microscopic ◽  
Before And After ◽  
Ultrastructural Modification

An electron-microscopic examination of bone marrow mitochondria derived from 10 patients before and after chloramphenicol (CAP) therapy has shown that CAP induces an ultrastructural modification resulting in an increase in the density of the mitochondrial matrix. These changes resemble the condensed mitochondrial configurations which have previously been interpreted in terms of electron transfer and oxidative phosphorylation. However, in the concentrations employed in this study, CAP has no effect on mitochondrial respiration or on oxidative phosphorylation, but is a potent inhibitor of mitochondrial protein synthesis. Evidence relating this effect of the drug to its myelotoxicity has been supported by a comparative study demonstrating lack of effect of a drug such as tetracycline which is not known to be myelotoxic, and the excellent correlation between the extensiveness of mitochondrial changes in the marrow and the serum level of free CAP. The results were confirmed in a parallel study on insect flight muscle mitochondria, in which the metabolic state under which the drug is administered can be con trolled and where the regular disposition of the mitochondrial cristae provides an ideal model for the study of configurational changes.

scholarly journals Maize pentatricopeptide repeat protein DEK53 is required for mitochondrial RNA editing at multiple sites and seed development

2020 ◽  
Vol 71 (20) ◽  
pp. 6246-6261 ◽  
Author(s):  
Dawei Dai ◽  
Lifang Jin ◽  
Zhenzhen Huo ◽  
Shumei Yan ◽  
Zeyang Ma ◽  
...  
Keyword(s):  
Rna Editing ◽  
Protein Complexes ◽  
Plant Mitochondria ◽  
Mitochondrial Protein ◽  
Electron Microscopic Examination ◽  
Complex Iii ◽  
Mitochondrial Rna ◽  
Pentatricopeptide Repeat ◽  
Electron Microscopic ◽  
Ppr Protein

Abstract Pentatricopeptide repeat (PPR) proteins were identified as site-specific recognition factors for RNA editing in plant mitochondria and plastids. In this study, we characterized maize (Zea mays) kernel mutant defective kernel 53 (dek53), which has an embryo lethal and collapsed endosperm phenotype. Dek53 encodes an E-subgroup PPR protein, which possesses a short PLS repeat region of only seven repeats. Subcellular localization analysis indicated that DEK53 is localized in the mitochondrion. Strand- and transcript-specific RNA-seq analysis showed that the dek53 mutation affected C-to-U RNA editing at more than 60 mitochondrial C targets. Biochemical analysis of mitochondrial protein complexes revealed a significant reduction in the assembly of mitochondrial complex III in dek53. Transmission electron microscopic examination showed severe morphological defects of mitochondria in dek53 endosperm cells. In addition, yeast two-hybrid and luciferase complementation imaging assays indicated that DEK53 can interact with the mitochondrion-targeted non-PPR RNA editing factor ZmMORF1, suggesting that DEK53 might be a functional component of the organellar RNA editosome.

Calcium and contractions of isolated smooth muscle cells from rat myometrium

1987 ◽  
Vol 65 (9) ◽  
pp. 1966-1975 ◽  
Author(s):  
M. Kyozuka ◽  
J. Crankshaw ◽  
I. Berezin ◽  
S. M. Collins ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Electron Microscopic Examination ◽  
Muscle Cells ◽  
Isolated Cells ◽  
Electron Microscopic ◽  
Cell Shortening ◽  
Before And After ◽  
Intracellular Ca ◽  
Small Muscle

Smooth muscle cells were isolated from estrogenized rat myometrium by collagenase digestion. Electron microscopic examination and measurement of cell lengths by image-splitting micrometry were carried out after fixation with acrolein. Mean lengths of cells before and after isolation were 81.7 and 66.9 μm, respectively. Responses of cells were compared with contractions of isolated strips recorded isometrically. Effects of carbachol and KCl were examined in 2 mM Ca, 2 mM Ca + 4 mM EGTA, and 2 mM Ca + 10−8 M nitrendipine solution. Carbachol and KCl produced concentration-dependent shortening of isolated cells maximal at 30 s after addition. The concentrations of carbachol required to produce shortenings were about 100-fold less than those required to produce isometric contractions; but no major difference was observed in the concentration dependence of cell shortening and isometric contraction produced by potassium-induced depolarization. In 2 mM Ca solution, there was a phasic response, followed by a tonic response such that more than 50% of maximum cell shortening was maintained for 10 min. However, in 2 mM Ca + 4 mM EGTA or 10−8 M nitrendipine, the tonic contraction was abolished and cells rapidly relaxed after 30 s. If carbachol was added to cells after varying times in the EGTA-containing solution, the ability to initiate a contraction declined exponentially with a half-time of 160 s. Effects of depolarization by KCl were examined in 2 mM Ca plus nitrendipine and 2 mM Ca + 4 mM EGTA solution. Shortening occurred in 2 mM Ca solution by depolarization but not if nitrendipine was added. Though shortening was not observed in 2 mM Ca + 4 mM EGTA solution by KCl, subsequent addition of carbachol induced shortening. These results suggested that there was an intracellular Ca store site from which Ca was released by carbachol and which was not affected by depolarization in the absence of external Ca. No evidence was obtained that the contraction persists in Ca2+-free medium in isolated cells, which is in agreement with previous findings in small muscle strips in which only a similar transient response was obtained.

An Electron Microscope Study of the Outer Layers of Barley Leaves Infected with Rhynchosporium secalis

1974 ◽  
Vol 1 (2) ◽  
pp. 313 ◽  
Author(s):  
CC Ryan ◽  
CJ Grivell
Keyword(s):  
Cell Wall ◽  
Outer Layer ◽  
Electron Microscope Study ◽  
Electron Microscopic Examination ◽  
Ruthenium Red ◽  
Electron Microscopic ◽  
Before And After ◽  
Barley Leaves ◽  
Epidermal Cell Wall ◽  
Wall Following

An electron microscopic examination was made of barley leaves before and after infection by R. secalis. Ruthenium red was used as an electron-opaque stain for pectic material. In uninfected leaves the adaxial surface consisted of wax, cuticle, pectic and inner and outer layer of the epidermal cell wall. Following penetration, infecting hyphae grew between the pectic layer and outer layer of the epidermal wall. The pectic and cuticular layers remained largely intact in leaf lesions until conidia were produced, whereas the cell wall was degraded and replaced by hyphae.

scholarly journals A holistic insight of mycobacteriophage induced changes in mycobacterial cells

2021 ◽  
Author(s):  
Fatema Calcuttawala ◽  
Rahul Shaw ◽  
Arpita Sarbajna ◽  
Moumita Dutta ◽  
Saptarshi Sinha ◽  
...  
Keyword(s):  
Cell Death ◽  
Electron Microscopic Examination ◽  
Cellular Level ◽  
Electron Microscopic ◽  
Major Mechanism ◽  
Membrane Pores ◽  
Transmission Electron ◽  
Before And After ◽  
Microscopic Studies ◽  
Induced Changes

Mycobacteriophages are phages that interact with mycobacteria resulting in their killing. Although lysis is the major mechanism by which mycobacteriophages cause cell death, other mechanisms may also be involved. The present study was in i tiated with the objective of investigating the changes that take place at the cellular level following the infection of mycobacterial cells by phage D29.  To investigate th is issue, we took recourse to performing immunofluorescence and electron microscopic studies . Transmission electron microscopic examination reveal ed the adsorption of phages on to the surface of mycobacteria , f ollowing which penetration of the tail through the thick mycol o ic acid layer was seen . At later time points discrete populations of cells at different stages of lysis we re observed , which comprised of complete ly lys ed cells , in which the cells were fragmented and those at the early onset stage exhibited formation of membrane pores through which the phages and intracellular contents were released.   SEM results also indicate d that phages may come out through the entire surface of the cell, or alternatively through gaps in the surface. In some of the images we observed structures that apparently resembled membrane blebs which are normally encountered when cells undergo programmed cell death (PCD). In addition, we observed significant increase in DNA fragmentation as well as membrane depolarization, which are also indicative of occurrence of PCD. As several bacterial PCD pathways are mediated by the toxin-antitoxin (TA) modules, the expression profile of all the TA systems was examined before and after phage infection. Apart from specifically addressing the issue of PCD in mycobacteriophage infected cells, this investigation has led to the development of facile tools necessary for investigating mycobacteriophage-mycobacteria interactions by means of microscopic methods.

The Effect of Bovine Lung Heparin on Normal Human Platelets as Measured by Electronic Particle Size Analysis

1982 ◽  
Vol 47 (01) ◽  
pp. 005-007 ◽  
Author(s):  
Margaret R McLean ◽  
Lawrence L Hause
Keyword(s):  
Particle Size ◽  
Microscopic Examination ◽  
Platelet Rich Plasma ◽  
Electron Microscopic Examination ◽  
Particle Size Analysis ◽  
Human Platelets ◽  
Size Analysis ◽  
Electron Microscopic ◽  
Before And After ◽  
Normal Human

SummaryThe response of normal human platelets to treatment with bovine lung heparin was evaluated using electronic particle size analysis and aggregometry. Samples for electronic particle size analysis were obtained both before and after the addition of heparin to platelet-rich plasma (PRP). The number of single platelets decreased significantly after the addition of heparin to PRP obtained from 22 individuals. This decrease averaged 18% in 19 samples which did not show a significant increase in transmittance and was at least 70% in 3 samples which showed a significant increase in transmittance. The size distribution of single platelets was not significantly altered. In addition, electron microscopic examination revealed that platelets treated with heparin are activated.

MITOCHONDRIA FROM LIPOMYCES LIPOFER

1965 ◽  
Vol 43 (5) ◽  
pp. 561-571 ◽  
Author(s):  
H. M. C. Heick ◽  
H. B. Stewart
Keyword(s):  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Microscopic Examination ◽  
Electron Microscopic Examination ◽  
The Other ◽  
Particulate Fraction ◽  
Thiamine Pyrophosphate ◽  
Electron Microscopic ◽  
Lipomyces Lipofer ◽  
Homogeneous Preparation

Protoplasts of Lipomyces lipofer were ruptured by decompression in a French pressure cell. A particulate fraction sedimenting at 17,000 × g in saline or sucrose media contained the bulk of the substrate-dependent oxidative activity and was capable of phosphorylation. Particle fractions isolated in sucrose required supplementation with ATP and Mg2+while fractions from saline isolations required, in addition, NAD and cytochrome c. NADP and thiamine pyrophosphate had small or negligible effects in the presence of the other cofactors. Oxidative phosphorylation occurred most efficiently in particles isolated in sucrose, but in no case did the P/O ratio exceed 1.6. Electron microscopic examination of the sucrose-isolated fraction showed it to be a relatively homogeneous preparation of mitochondria which appear more "native" after incubation with substrate than immediately after isolation.

Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland

1978 ◽  
Vol 36 (2) ◽  
pp. 46-47
Author(s):  
Jan Zarzycki ◽  
Joseph Szroeder
Keyword(s):  
Mammary Gland ◽  
Protein Denaturation ◽  
Chemical Constituents ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Mouse Mammary Gland ◽  
Electron Microscopic ◽  
Preparation Methods ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.

A Comparative Study of Fractographic Replicas

1974 ◽  
Vol 32 ◽  
pp. 566-567
Author(s):  
Loren Anderson ◽  
Pat Pizzo ◽  
Glen Haydon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Direct Examination ◽  
Electron Microscopic ◽  
Reliable Technique ◽  
Service Failures ◽  
Transmission Electron ◽  
Mode Of Failure ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Transmission electron microscopy of replicas has long been used to study the fracture surfaces of components which fail in service. Recently, the scanning electron microscope (SEM) has gained popularity because it allows direct examination of the fracture surface. However, the somewhat lower resolution of the SEM coupled with a restriction on the sample size has served to limit the use of this instrument in investigating in-service failures. It is the intent of this paper to show that scanning electron microscopic examination of conventional negative replicas can be a convenient and reliable technique for determining mode of failure.

Novel methods for demonstrating osseointegration of hydroxylapatite-coated titanium hip prostheses

1991 ◽  
Vol 49 ◽  
pp. 34-35 ◽  
Author(s):  
P. Frayssinet ◽  
J. Hanker ◽  
D. Hardy ◽  
B. Giammara
Keyword(s):  
Hip Prosthesis ◽  
Ethanol Concentration ◽  
Bone Matrix ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Hip Prostheses ◽  
Cellular Inclusions ◽  
Microscopic Studies ◽  
Diamond Saw ◽  
Plasma Sprayed

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed methods allowing light and electron microscopic studies as well as microanalysis of the interface between bone and a metal biomaterial coated by plasma-sprayed hydroxylapatite(HA) ceramic.An HA-coated titanium hip prosthesis (Corail, Landos, France), which had been implanted for two years, was removed after death (unrelated to the orthopaedic problem). After fixation it was dehydrated in solutions of increasing ethanol concentration prior to embedment in polymethylmethacrylate(PMMA). Transverse femur sections were obtained with a diamond saw and the sections then carefully ground to a thickness of 200 microns. Plastic-embedded sections were stained for calcium with a silver methenamine modification of the von Kossa method for calcium staining and coated by carbon. They have been examined by back-scatter SEM on an ISI-SS60 operated at 25 KV. EDAX has been done on cellular inclusions and extracellular bone matrix.

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