scholarly journals Isolation and ultrastructural characterization of secretory mutants of Tetrahymena thermophila

1983 ◽  
Vol 64 (1) ◽  
pp. 49-67 ◽  
Author(s):  
E. Orias ◽  
M. Flacks ◽  
B.H. Satir
Keyword(s):  
Electron Microscopy ◽  
Tetrahymena Thermophila ◽  
Freeze Fracture ◽  
Regulatory Mechanisms ◽  
Genetic Dissection ◽  
Intramembrane Particle ◽  
Particle Array ◽  
Normal Number ◽  
Ultrastructural Characterization

Isolation of 14-secretory mutants (exo-) of Tetrahymena thermophila and ultrastructural characterization (freeze-fracture and thin-section) of two of these (SB255 and SB258) are described. The site of secretion is marked by an intramembrane particle array, the rosette, beneath which the secretory organelle rests. Using Alcian Blue (8GS) as a secretagogue, a screening procedure for exo- cells was developed. Of the resulting 14 clones isolated, 10 are stable and have a tight mutant phenotype. Two of these, SB255 and SB258, lack assembled rosettes. Electron microscopy shows that SB255 has a reduced total number of mucocysts, whereas SB258 appears to have the normal number. This study demonstrates a useful eukaryotic model with which to study by genetic dissection the regulatory mechanisms involved in membrane events in secretion.

Cryomicroscopy of multiphase latices

1991 ◽  
Vol 49 ◽  
pp. 1060-1061
Author(s):  
O. L. Shaffer ◽  
M.S. El-Aasser ◽  
C. L. Zhao ◽  
M. A. Winnik ◽  
R. R. Shivers
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Freeze Fracture ◽  
Particle Morphology ◽  
Second Stage ◽  
Transmission Electron ◽  
Important Approach ◽  
Carbon Coated ◽  
Preparation Techniques

Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.

Protein secretion in Tetrahymena thermophila: characterization of the secretory mutant strain SB281

1985 ◽  
Vol 78 (1) ◽  
pp. 49-65 ◽  
Author(s):  
N.J. Maihle ◽  
B.H. Satir
Keyword(s):  
Plasma Membrane ◽  
Mutant Strain ◽  
Protein Secretion ◽  
Tetrahymena Thermophila ◽  
Freeze Fracture ◽  
Size Class ◽  
Secretory Product ◽  
Wild Type ◽  
Intramembrane Particle ◽  
Mutant Cells

The ciliated protozoon Tetrahymena thermophila contains membrane-bounded secretory organelles termed mucocysts, the release of which has previously been characterized ultrastructurally as a model system for the events occurring during membrane fusion and protein secretion. Recently, a series of secretory mutant strains of Tetrahymena has been isolated following mutagenesis of a parental wild-type strain designated SB210. In this study, the correlates of non-release in one unique mutant strain of this series, designated SB281, are described. SB281 appears to express a diminished (undetectable) level of the major 34000 Mr proteinaceous secretory product of Tetrahymena, as determined by Western immunoblot analysis and indirect immunofluorescence labelling. Thin-section electron-microscopic studies of these cells reveal that they possess no docked or free mature mucocysts. In addition, freeze-fracture electron microscopy demonstrates that an intramembrane particle array termed the rosette, present in the plasma membrane of wild-type cells above sites of docked mucocysts, is absent in the plasma membrane of mutant SB281 cells. A morphometric analysis of intramembrane particles in the plasma membrane of both wild-type and mutant cells indicates that both strains have a similar intramembrane particle density in both leaflets of the the plasma membrane. Although assembled rosettes are missing in the plasma membrane of mutant cells, a 15 nm intramembrane particle size class does exist in the plasma membrane of the mutant, but this size class is significantly reduced in number relative to wild-type.

Ultrastructural characterization of the new NG97ht human-derived glioma cell line using two different electron microscopy technical procedures

2009 ◽  
Vol 72 (4) ◽  
pp. 310-316 ◽  
Author(s):  
Camila Maria Longo Machado ◽  
Tatiane Queiroz Zorzeto ◽  
Juares E. Romero Bianco ◽  
Renata Giardini Rosa ◽  
Selma Candelaria Genari ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Glioma Cell ◽  
Glioma Cell Line ◽  
Ultrastructural Characterization

scholarly journals Characterization of Scardovia wiggsiae Biofilm by Original Scanning Electron Microscopy Protocol

2020 ◽  
Vol 8 (6) ◽  
pp. 807 ◽  
Author(s):  
Maurizio Bossù ◽  
Laura Selan ◽  
Marco Artini ◽  
Michela Relucenti ◽  
Giuseppe Familiari ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Species ◽  
High Vacuum ◽  
Innovative Strategies ◽  
Ultrastructural Characterization ◽  
Severe Manifestation ◽  
Original Procedure ◽  
Scanning Electron

Early childhood caries (ECC) is a severe manifestation of carious pathology with rapid and disruptive progression. The ECC microbiota includes a wide variety of bacterial species, among which is an anaerobic newly named species, Scardovia wiggsiae, a previously unidentified Bifidobacterium. Our aim was to provide the first ultrastructural characterization of S. wiggsiae and its biofilm by scanning electron microscopy (SEM) using a protocol that faithfully preserved the biofilm architecture and allowed an investigation at very high magnifications (order of nanometers) and with the appropriate resolution. To accomplish this task, we analyzed Streptococcus mutans’ biofilm by conventional SEM and VP-SEM protocols, in addition, we developed an original procedure, named OsO4-RR-TA-IL, which avoids dehydration, drying and sputter coating. This innovative protocol allowed high-resolution and high-magnification imaging (from 10000× to 35000×) in high-vacuum and high-voltage conditions. After comparing three methods, we chose OsO4-RR-TA-IL to investigate S. wiggsiae. It appeared as a fusiform elongated bacterium, without surface specialization, arranged in clusters and submerged in a rich biofilm matrix, which showed a well-developed micro-canalicular system. Our results provide the basis for the development of innovative strategies to quantify the effects of different treatments, in order to establish the best option to counteract ECC in pediatric patients.

Ultrastructural characterization of cytomegalovirus infected and interferon producing human foreskin cells

1990 ◽  
Vol 48 (3) ◽  
pp. 312-313
Author(s):  
J. Rodriquez ◽  
T.O. Moninger ◽  
D. Walker ◽  
K. C. Moore
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Cytomegalovirus ◽  
Beta Interferon ◽  
Ultrastructural Characterization ◽  
Scanning Electron

Published work indicates that human cytomegalovirus (CMV) is sensitive to the action of beta interferon (HuIFNb) and can induce the production of INF in cultures of human foreskin (HF) cells. These findings are consistent with a role for endogenous IFN in the establishment and maintenance of persistent CMV infections. Moreover HF cells can be primed with IFN and these primed cells can be induced to produce large concentrations of IFN after exposure to CMV. These findings support the hypothesis formulated to explain the larger-than-expected concentrations of IFN detected in cultures exposed to low MOIs (<0.01), namely, that the phenomenon observed involved endogenous priming, that is production of IFN by the small percentage of the cells infected by the inoculum virus. This results in priming of the remaining cells by IFN, and finally induction of the primed cells by progeny CMV released from the cells infected originally.To lend support to this hypothesis we will follow the attachment, penetration, and release stages of the CMV replication by transmission and scanning electron microscopy.

Electron Microscopy Findings inN-Methyl-N-Nitrosourea-Induced Mammary Tumors

2016 ◽  
Vol 22 (5) ◽  
pp. 1056-1061
Author(s):  
Ana I. Faustino-Rocha ◽  
Ana M. Calado ◽  
Adelina Gama ◽  
Rita Ferreira ◽  
Mário Ginja ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rat Model ◽  
Mammary Tumors ◽  
Female Rats ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Chemically Induced ◽  
Ultrastructural Characterization ◽  
Human Mammary Tumors

AbstractAlthough the rat model of mammary tumors chemically induced byN-methyl-N-nitrosourea (MNU) has been frequently used by several research teams, there is a lack of ultrastructural studies in this field. The main aim of this work was to perform an ultrastructural characterization of MNU-induced mammary tumors in female rats. Some alterations previously reported in human mammary tumors, such as nucleus size and shape, accumulation of heterochromatin in the perinuclear region, and interdigitating cytoplasmic processes between cancer cells were also observed in MNU-induced mammary tumors. Although a low number of samples were analyzed by transmission electron microscopy in the present study, we consider that it may contribute to a better understanding of MNU-induced mammary carcinogenesis in a rat model. The ultrastructural characteristics of the two most frequently diagnosed mammary carcinomas described in the present work can be useful to differentiate them from other histological patterns. In addition, the loss of cytoplasm in neoplastic cells and formation of vacuoles were described.

Effect of Cerophyl growth medium on exocytosis in Tetrahymena thermophila

1985 ◽  
Vol 78 (1) ◽  
pp. 23-48
Author(s):  
D.M. Pesciotta ◽  
B.H. Satir
Keyword(s):  
Cell Division ◽  
De Novo ◽  
Tetrahymena Thermophila ◽  
Freeze Fracture ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Particle Array ◽  
Proteose Peptone ◽  
Section Electron ◽  
Cell Changes

Culturing the ciliate Tetrahymena thermophila in Cerophyl has provided an opportunity for studying the assembly and/or synthesis of the intramembrane particle array, the rosette, which marks the site of exocytosis in these cells. Cultures grown in this medium cease cell division after only 12h and enter ‘stationary phase’ earlier (12h of growth) relative to growth in standard medium (proteose peptone). In addition, the cell changes from the normally observed pear-shaped body to a thinner more ellipsoid form. Despite the initial similarities to starving cells, several differences are observed in the Cerophyl-grown cells. One is that cell size remains constant for at least 72h in contrast to starved cells. Secondly, in spite of this block in cell division, results from freeze-fracture replicas of the cell membrane of these cells show that they continue to assemble rosettes, the number of which increases approximately six times, from 0.34 rosette/microgram2 to 2.1 rosettes/microgram2. Addition of the protein synthesis inhibitor, cycloheximide (6h exposure), during growth in Cerophyl shows that 70% of rosettes can be assembled, despite the blockage of translation, by using pre-existing component(s) from a pool. The remaining 30% must involve de novo synthesis of one or more components; this percentage can be increased with longer exposure to the drug. Thirdly, an apparent increase in the number of mucocysts is observed by thin-section electron microscopy. At first (12–24h) only docked mucocysts seem to accumulate in the cell. However, by 36h a considerable increase seems to have taken place, particularly in the number of mucocysts located in the cytoplasm. In the cycloheximide-treated cells this increase in mucocysts begins to be blocked after 6h of exposure to the drug. These observations are in agreement with the results obtained from the freeze-fracture data on the concomitant increase in number of rosettes. This system therefore offers the first possibility of exploring the biosynthesis of these components.

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