scholarly journals Chromate Reduction in Serratia marcescens Isolated from Tannery Effluent and Potential Application for Bioremediation of Chromate Pollution

2002 ◽  
Vol 2 ◽  
pp. 972-977 ◽  
Author(s):  
M.A. Mondaca ◽  
V. Campos ◽  
R. Moraga ◽  
C.A. Zaror
Keyword(s):  
Natural Waters ◽  
Waste Treatment ◽  
Environmental Concern ◽  
Electron Microscopic Examination ◽  
Tannery Effluent ◽  
Chromate Reduction ◽  
Bacterial Cells ◽  
Electron Microscopic ◽  
Treatment Processes ◽  
Transmission Electron

Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI) and Cr(III) are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI) to Cr(III), and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010cfu attached per milligram of activated carbon. These findings demonstrate that immobilizedS. marcescensmight be used in industrial waste treatment processes.

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.

Electrophoretic and electron microscopic examination of the adductor and diductor muscles of an articulate brachiopod, Terebratalia transversa

1982 ◽  
Vol 60 (4) ◽  
pp. 550-559 ◽  
Author(s):  
William P. Eshleman ◽  
Jerrel L. Wilkens ◽  
Michael J. Cavey
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Electron Microscopic Examination ◽  
Light Chains ◽  
Electron Microscopic ◽  
Electrophoretic Patterns ◽  
Transmission Electron ◽  
Adductor Muscles ◽  
Regulation Of Contraction

The proteins of the striated adductor muscles, smooth adductor muscles, and diductor muscles of the articulate brachiopod Terebratalia transversa have been examined by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Electrophoretic patterns indicate the presence of paramyosin in all of these valve muscles. Tentative identification has also been made of the proteins responsible for actin and for myosin regulation of contraction (troponin–tropomyosin and myosin light chains, respectively). The myofilaments of the striated adductor cells, smooth adductor cells, and diductor cells have been characterized by transmission electron microscopy. The smooth adductor cells and the diductor cells exhibit very thick myofilaments which are fusiform in shape, exceptionally long, and axially banded. Morphological features of these thick myofilaments are consistent with those of paramyosin filaments found in other muscles and myoepithelia. Although the striated adductor cells contain paramyosin, it is not manifest in the thick myofilaments.

scholarly journals Internalization of Staphylococcus aureusby Endothelial Cells Induces Apoptosis

1998 ◽  
Vol 66 (12) ◽  
pp. 5994-5998 ◽  
Author(s):  
Barbara E. Menzies ◽  
Iordanka Kourteva
Keyword(s):  
Endothelial Cells ◽  
Umbilical Vein ◽  
Electron Microscopic Examination ◽  
Cytochalasin D ◽  
Nuclear Morphology ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Endothelial Cell Death ◽  
Umbilical Vein Endothelial Cells

ABSTRACT The ability of Staphylococcus aureus to invade and survive within endothelial cells is believed to contribute to its propensity to cause persistent endovascular infection with endothelial destruction. In the present study, we show that following invasion of human umbilical vein endothelial cells, intracellular S. aureus organisms remain viable over a 72-h period and, as determined by transmission electron microscopic examination, that the bacteria exist within vacuoles and free within the cytoplasm. We also demonstrate that endothelial cell death following S. aureusinvasion occurs at least in part by apoptosis as shown by DNA fragmentation and changes in nuclear morphology. Apoptotic changes were evident as early as 1 h after infection of endothelial cells. Internalization of S. aureus rather than adherence appears to be necessary, since use of the phagocytosis inhibitor cytochalasin D prevented apoptosis. UV-killed staphylococci, although retaining the capacity to be internalized, were not capable of inducing apoptosis, suggesting that apoptosis is dependent upon a factor associated with viable organisms. The studies demonstrate that viable intracellularS. aureus induces apoptosis of endothelial cells and that internalized staphylococci can exist free within the cytoplasm.

Ultrastructural studies of cartilage in genetic disorders of skeletal growth

1978 ◽  
Vol 36 (2) ◽  
pp. 668-669
Author(s):  
D. O. Sillence ◽  
D. L. Rimoin ◽  
Ruth Silberberg
Keyword(s):  
Genetic Disorders ◽  
Electron Microscopic Examination ◽  
Uranyl Acetate ◽  
Osmic Acid ◽  
Electron Microscopic ◽  
Skeletal Dysplasias ◽  
Ultrastructural Studies ◽  
Low Viscosity ◽  
Transmission Electron ◽  
Cacodylate Buffer

The human skeletal dysplasias are an heterogeneous group of heritable connective tissue disorders associated with abnormalities in the size and shape of the limbs, trunk and/or skull which frequently result in disproportionate short stature. In recent years it has become apparent that these comprise over 50 distinct conditions with a variety of subtypes distinguished on clinical and radiological grounds. We have investigated the pathogenesis of these conditions in over 100 patients by direct transmission electron microscopic examination of chondro-osseous tissue. Some of the ultrastructural studies have been previously reported.Small biopsies of chondro-osseous junction were collected for electron microscopy from the rib or iliac crest of patients with skeletal dysplasias or from normal controls at the time of surgery. These were cut into small blocks and fixed for one hour in either 5% glutaraldehyde in white's buffer or directly in 1% osmic acid in White's buffer or a modified Karnovsky's fixative, (2. 5% paraformaldehyde, 2. 5% glutaraldehyde, 2. 5mM calcium in cacodylate buffer). Subsequent processing included osmium fixation, block staining with uranyl acetate and embedding in Araldite or Spurr's low viscosity resin (firm composition). Sections were cut with glass knives or diamond knives. The latter produced sections which were much more even in thickness, permitting more consistent appraisal of matrix features.

A Rapid Method for Electron Microscopic Examination of Biological Specimens

1971 ◽  
Vol 29 ◽  
pp. 486-487
Author(s):  
Glenn Stoner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Simple Procedure ◽  
Contact Point ◽  
Electron Microscopic Examination ◽  
Test Solution ◽  
Biological Applications ◽  
Electron Microscopic ◽  
Preparation Time ◽  
Transmission Electron

The purpose of this paper is to demonstrate the use of a method which reduces the sample preparation time for transmission electron microscopy studies to about one minute.The relatively simple procedure is as follows: When a sample is desired, place 1 mℓ test solution in a 2-5 mℓ container, add 0.1 mℓ of a solution of 0.3 mg/mℓ fibrinogen, immediately insert a 400 mesh E.M. grid held by forceps, withdraw immediately, blot (at the tweezer tip-grid contact point) with filter paper, blow dry with a lab drier, add one drop of stain (2% urinal acetate), blot and blow dry in the above manner. Then immediately insert in the pre-pump chamber of the E.M.The above process has been used by the author in a variety of biological applications, from studies of fibrin growth from fibrinogen to identification of unknown viruses. The accompaning figures for T4, bacteriophage are given simply to demonstrate the method.

Peculiarities of the ultrastructure of mixed biofilms of the causing agent of diphtheria and conditionally pathogenic microorganisms isolated from the human respiratory tract

2021 ◽  
Vol 66 (10) ◽  
pp. 623-628
Author(s):  
V. N. Gerasimov ◽  
Galina Georgievna Kharseeva ◽  
O. S. Sherbataya ◽  
S. A. Kotov ◽  
A. V. Chepusova
Keyword(s):  
Respiratory Tract ◽  
Electron Microscopic Examination ◽  
The Body ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Human Respiratory Tract ◽  
Electron Microscopic ◽  
Opportunistic Bacteria ◽  
Epidemic Period ◽  
High Level

In the post-epidemic period, the circulation of the causative agent of diphtheria in the population is maintained due to the carrier of bacteria. Entering an organism with a high level of antitoxic immunity, the pathogen enters into intermicrobial interactions with representatives of the opportunistic microflora inhabiting the respiratory tract and forms a biofilm. Materials and methods. Modeling of the biofilm formation process was carried out using the strains C.diphtheriae gravis tox+№. 665, C.pseudodiphtheriticum, S.aureus. Biofilm samples were placed on the stage of a scanning electron microscope and gold-sputtered in an EicoIB-3 ioncoater vacuum deposition unit (Eico, Japan) at an ion current of 6-8 mA. The samples obtained were examined in a JEOL 6510LB scanning electronmicroscope. («JEOL» company, Japan) at an accelerating voltage of 30 kV. Results. Electron microscopic examination of samples of biofilms C. diphtheriae gravis tox+ № 665 and opportunistic microorganisms shows groups of 2-7 young bacterial cells packed into a single microcapsule. Much more voluminous accumulations of bacterial cells (more than 10-12) are typical for biofilm samples represented by C. diphtheriae gravis tox+№ 665 and S. aureus cells. On the surface of the biofilm, young bacterial cells with an intact structure are located at various stages of active division. The conglomerates of bacterial cells, covered with a common intermicrobial matrix, adhere tightly to each other and form a multilayer biofilm. Conclusion. Features of the ultrastructure of biofilms containing strains of C. diphtheriae and opportunistic bacteria, especially antibiotic-resistant bacteria inhabiting the respiratory tract, can contribute to long-term persistence of the pathogen of diphtheria in the body. They not only significantly complicate the access of antibacterial drugs, but also interfere with the isolation of C.diphtheriae during bacteriological research.

Sign in / Sign up

Export Citation Format

Share Document