scholarly journals REJUVENATION OF MELOSIRA GRANULATA (BACILLARIOPHYCEAE) RESTING CELLS FROM THE ANOXIC SEDIMENTS OF DOUGLAS LAKE, MICHIGAN, II. ELECTRON MICROSCOPY

1986 ◽  
Vol 22 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Lake Michigan ◽  
Resting Cells ◽  
Anoxic Sediments

Ultrastructure of Melosira resting cell rejuvenation

1984 ◽  
Vol 42 ◽  
pp. 734-735
Author(s):  
C. E. M. Bourne ◽  
L. Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Lake Michigan ◽  
Light And Electron Microscopy ◽  
Resting Cells ◽  
Planktonic Diatoms ◽  
Resting Cell ◽  
Vegetative Survival ◽  
Cytological Changes ◽  
Recent Attention ◽  
Freshwater Diatom

Much recent attention has been focused on vegetative survival forms of planktonic diatoms and other algae. There are several reports of extended vegetative survival of the freshwater diatom Melosira in lake sediments. In contrast to those diatoms which form a morphologically distinct resistant spore, Melosira is known to produce physiological resting cells that are indistinguishable in outward morphology from actively growing cells.We used both light and electron microscopy to document and elucidate the sequence of cytological changes during the transition from resting cells to actively growing cells in a population of Melosira granulata from Douglas Lake, Michigan sediments collected in mid-July of 1983.

scholarly journals Liquid-phase electron microscopy of molecular drug response in breast cancer cells reveals irresponsive cell subpopulations related to lack of HER2 homodimers

2017 ◽  
Vol 28 (23) ◽  
pp. 3193-3202 ◽  
Author(s):  
Diana B. Peckys ◽  
Ulrike Korf ◽  
Stefan Wiemann ◽  
Niels de Jonge
Keyword(s):  
Breast Cancer ◽  
Electron Microscopy ◽  
Drug Resistance ◽  
Liquid Phase ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Plasma Membranes ◽  
Drug Binding ◽  
Resting Cells ◽  
Cell Heterogeneity

The development of drug resistance in cancer poses a major clinical problem. An example is human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer often treated with anti-HER2 antibody therapies, such as trastuzumab. Because drug resistance is rooted mainly in tumor cell heterogeneity, we examined the drug effect in different subpopulations of SKBR3 breast cancer cells and compared the results with those of a drug-resistant cell line, HCC1954. Correlative light microscopy and liquid-phase scanning transmission electron microscopy were used to quantitatively analyze HER2 responses upon drug binding, whereby many tens of whole cells were imaged. Trastuzumab was found to selectively cross-link and down-regulate HER2 homodimers from the plasma membranes of bulk cancer cells. In contrast, HER2 resided mainly as monomers in rare subpopulations of resting and cancer stem cells (CSCs), and these monomers were not internalized after drug binding. The HER2 distribution was hardly influenced by trastuzumab for the HCC1954 cells. These findings show that resting cells and CSCs are irresponsive to the drug and thus point toward a molecular explanation behind the origin of drug resistance. This analytical method is broadly applicable to study membrane protein interactions in the intact plasma membrane, while accounting for cell heterogeneity.

scholarly journals Local variations of HER2 dimerization in breast cancer cells discovered by correlative fluorescence and liquid electron microscopy

2015 ◽  
Vol 1 (6) ◽  
pp. e1500165 ◽  
Author(s):  
Diana B. Peckys ◽  
Ulrike Korf ◽  
Niels de Jonge
Keyword(s):  
Breast Cancer ◽  
Electron Microscopy ◽  
Fluorescence Microscopy ◽  
Cancer Cells ◽  
Single Molecule ◽  
Breast Cancer Cells ◽  
Pair Correlation ◽  
Resting Cells ◽  
Membrane Topography ◽  
Cancer Aggressiveness

The formation of HER2 homodimers plays an important role in breast cancer aggressiveness and progression; however, little is known about its localization. We have studied the intra- and intercellular variation of HER2 at the single-molecule level in intact SKBR3 breast cancer cells. Whole cells were visualized in hydrated state with correlative fluorescence microscopy and environmental scanning electron microscopy (ESEM). The locations of individual HER2 receptors were detected using an anti-HER2 affibody in combination with a quantum dot (QD), a fluorescent nanoparticle. Fluorescence microscopy revealed considerable differences of HER2 membrane expression between individual cells and between different membrane regions of the same cell (that is, membrane ruffles and flat areas). Subsequent ESEM of the corresponding cellular regions provided images of individually labeled HER2 receptors. The high spatial resolution of 3 nm and the close proximity between the QD and the receptor allowed quantifying the stoichiometry of HER2 complexes, distinguishing between monomers, dimers, and higher-order clusters. Downstream data analysis based on calculating the pair correlation function from receptor positions showed that cellular regions exhibiting membrane ruffles contained a substantial fraction of HER2 in homodimeric state. Larger-order clusters were also present. Membrane areas with homogeneous membrane topography, on the contrary, displayed HER2 in random distribution. Second, HER2 homodimers appeared to be absent from a small subpopulation of cells exhibiting a flat membrane topography, possibly resting cells. Local differences in homodimer presence may point toward functional differences with possible relevance for studying metastasis and drug response.

scholarly journals Examination of the surface microlayer of lake michigan using scanning electron microscopy

Micron (1969) ◽  
1982 ◽  
Vol 13 (4) ◽  
pp. 457-458 ◽  
Author(s):  
Diane lazinsky ◽  
Karen Erstfeld† ◽  
Clifford P. Rice ◽  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lake Michigan ◽  
Surface Microlayer ◽  
Scanning Electron

scholarly journals Reduction of Technetium by Desulfovibrio desulfuricans: Biocatalyst Characterization and Use in a Flowthrough Bioreactor

1999 ◽  
Vol 65 (6) ◽  
pp. 2691-2696 ◽  
Author(s):  
J. R. Lloyd ◽  
J. Ridley ◽  
T. Khizniak ◽  
N. N. Lyalikova ◽  
L. E. Macaskie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Enzyme Activity ◽  
Electron Donor ◽  
Membrane Bioreactor ◽  
Desulfovibrio Desulfuricans ◽  
Electron Donors ◽  
Resting Cells ◽  
Transmission Electron ◽  
Oxygen Transmission

ABSTRACT Resting cells of Desulfovibrio desulfuricans coupled the oxidation of a range of electron donors to Tc(VII) reduction. The reduced technetium was precipitated as an insoluble low-valence oxide. The optimum electron donor for the biotransformation was hydrogen, although rapid rates of reduction were also supported when formate or pyruvate was supplied to the cells. Technetium reduction was less efficient when the growth substrates lactate and ethanol were supplied as electron donors, while glycerol, succinate, acetate, and methanol supported negligible reduction. Enzyme activity was stable for several weeks and was insensitive to oxygen. Transmission electron microscopy showed that the radionuclide was precipitated at the periphery of the cell. Cells poisoned with Cu(II), which is selective for periplasmic but not cytoplasmic hydrogenases, were unable to reduce Tc(VII), a result consistent with the involvement of a periplasmic hydrogenase in Tc(VII) reduction. Resting cells, immobilized in a flowthrough membrane bioreactor and supplied with Tc(VII)-supplemented solution, accumulated substantial quantities of the radionuclide when formate was supplied as the electron donor, indicating the potential of this organism as a biocatalyst to treat Tc-contaminated wastewaters.

Platinum Compounds as Stains for Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 230-231
Author(s):  
S. K. Aggarwal ◽  
P. McAllister ◽  
R. W. Wagner ◽  
B. Rosenberg
Keyword(s):  
Electron Microscopy ◽  
Hela Cells ◽  
Uranyl Acetate ◽  
Sarcoma 180 ◽  
Platinum Compounds ◽  
Kb Cells ◽  
En Bloc ◽  
Human Lymphoma ◽  
Ultrathin Sections ◽  
Blue Coloration

Uranyl acetate has been used as an electron stain for en bloc staining as well as for staining ultrathin sections in conjunction with various lead stains (Fig. 1). Present studies reveal that various platinum compounds also show promise as electron stains. Certain platinum compounds have been shown to be effective anti-tumor agents. Of particular interest are the compounds with either uracil or thymine as one of the ligands (cis-Pt(II)-uracil; cis-Pt(II)-thymine). These compounds are amorphous, highly soluble in water and often exhibit an intense blue coloration. These compounds show enough electron density to be used as stains for electron microscopy. Most of the studies are based on various cell lines (human AV, cells, human lymphoma cells, KB cells, Sarcoma-180 ascites cells, chick fibroblasts and HeLa cells) while studies on tissue blocks are in progress.

Immune Electron Microscopy (IEM) of a Canine Adeno-Associated Virus

1974 ◽  
Vol 32 ◽  
pp. 256-257
Author(s):  
Gunter F. Thomas ◽  
M. David Hoggan
Keyword(s):  
Electron Microscopy ◽  
Cell Cultures ◽  
Complement Fixation ◽  
Hepatitis Virus ◽  
Wide Distribution ◽  
Immune Electron Microscopy ◽  
Adeno Associated Virus ◽  
Virus Like Particle ◽  
Dog Kidney ◽  
Green Monkeys

In 1968, Sugimura and Yanagawa described a small 25 nm virus like particle in association with the Matsuda strain of infectious canine hepatitis virus (ICHV). Domoto and Yanagawa showed that this particle was dependent on ICHV for its replication in primary dog kidney cell cultures (PDK) and was resistant to heating at 70°C for 10 min, and concluded that it was a canine adeno-associated virus (CAAV). Later studies by Onuma and Yanagawa compared CAAV with the known human serotypes (AAV 1, 2, 3) and AAV-4, known to be associated with African Green Monkeys. Using the complement fixation (CF) test, they found that CAAV was serologically related to AAV-3 and had wide distribution in the dog population of Japan.

High Voltage Electron Microscopy of Ion-Milled Dental Enamel

1974 ◽  
Vol 32 ◽  
pp. 60-61
Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Third Molar ◽  
Polarized Light ◽  
Dental Enamel ◽  
Longitudinal Section ◽  
Ion Milling ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

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