scholarly journals CONCOMITANT EFFECTS OF INSULIN ON SURFACE MEMBRANE CONFORMATION AND POLYSOME PROFILES OF SERUM-STARVED BALB/C 3T3 FIBROBLASTS

1974 ◽  
Vol 61 (1) ◽  
pp. 95-106 ◽  
Author(s):  
R. Blair Evans ◽  
Vera Morhenn ◽  
Albert L. Jones ◽  
Gordon M. Tomkins
Keyword(s):  
Electron Microscopy ◽  
Insulin Treatment ◽  
Cultured Cells ◽  
Unit Area ◽  
Surface Membrane ◽  
Serum Starvation ◽  
3T3 Fibroblasts ◽  
Transmission Electron ◽  
Polysome Profile ◽  
Logarithmic Growth

By scanning and transmission electron microscopy we have shown that insulin rapidly reversed changes in surface membrane conformation and polysome profile induced by the transfer of actively growing Balb/c 3T3 fibroblasts from a serum-containing to a serum-free medium. Morphometric analysis of polysome profiles revealed a 94% aggregation of total f ribosomes during logarithmic growth. This figure fell to 78% after 18 h of serum starvation. The number of f ribosomes per unit area of cytoplasm also fell. 1 h of insulin treatment restored aggregation to 92% and increased the number of f ribosomes per unit area of cytoplasm by 22%. Scanning electron microscopy of logarithmically growing cells revealed an abundance of surface microvilli, whereas serum starvation promoted a smooth surface with few microvilli. After 1 h of insulin treatment, microvilli reappeared with a distribution and subcellular organization characteristic of exponential growth. This study shows the combined and rapid effect of insulin on the regulation of polysome formation and the promotion of a specific surface membrane conformation in cultured cells. The observations are consistent with the knowledge that insulin, acting on the surface membrane, can influence such parameters as membrane transport, and the rates of protein and RNA synthesis.

The Effect Of Storage On Platelet Morpholog

1981 ◽  
Author(s):  
A Sturk ◽  
L M Burt ◽  
T Hakvoort ◽  
J W ten cate ◽  
N Crawford
Keyword(s):  
Electron Microscopy ◽  
Membrane Structure ◽  
Room Temperature ◽  
Surface Membrane ◽  
Platelet Concentrates ◽  
Room Temperature Storage ◽  
Short Survival ◽  
Transmission Electron ◽  
Temperature Storage ◽  
Morphological Correlation

Platelet concentrates were stored for one, two or three days at 4°C (unagitated) or room temperature (unagitated and linearly agitated). The morphology of platelets in platelet concentrates, directly after twice washing at room temperature and after 60 min incubation of the washed platelets at 37°C was investigated by both scanning and transmission electron microscopy.Platelets in the freshly prepared concentrates are slightly activated, i.e. show some pseudopod formation. At 4°C platelets rapidly loose their discoid shape. After three days their surface membrane shows extensive folding, they are slightly vacuolated and have lost most of their granules. Incubation of these cold-stored platelets at 37°C does not induce reversal to the discoid shape.Room temperature storage results in reversal of the slight initial platelet activation. After three days unagitated platelets are slightly more vacuolated than platelets stored with agitation. Room temperature storage usually results in remarkably well preserved, discoid platelets. Occasionally however, agitated platelet concentrates contain a high proportion of odd shaped cells. As platelets stored at 4°C did not became discoid after incubation at 37°, the altered membrane structure could provide an explanation for their short survival upon transfusion. Our results also provide a morphological correlation with the slightly better recovery and survival of platelets stored agitated vs.- non-agitated platelets at room temperature.

scholarly journals The Transport System of Nacre Components through the Surface Membrane of Gastropods

2016 ◽  
Vol 672 ◽  
pp. 103-112 ◽  
Author(s):  
Elena Macías-Sánchez ◽  
Antonio G. Checa ◽  
Marc G. Willinger
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Calcium Carbonate ◽  
Lamellar Structure ◽  
Surface Membrane ◽  
Organic Matrix ◽  
X Ray ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Electron Energy Loss

The surface membrane is a lamellar structure exclusive of gastropods that is formed during the shell secretion. It protects the surface of the growing nacre and it is located between the mantle epithelium and the mineralization compartment. At the mantle side of the surface membrane numerous vesicles provide material, and at the nacre side, the interlamellar membranes detach from the whole structure. Components of nacre (glycoproteins, polysaccharides and calcium carbonate) cross the structure to reach the mineralization compartment, but the mechanism by which this occurs is still unknown. In this paper we have investigated the ultrastructure of the surface membrane and the associated vesicle layer by means of Transmission Electron Microscopy. Electron Energy Loss Spectroscopy and Energy-dispersive X-ray Spectroscopy were used for elemental analysis. The analyses revealed the concentration of calcium in the studied structures: vesicles, surface membrane, and interlamellar membranes. We discuss the possible linkage of calcium to the organic matrix.

scholarly journals Imaging heterostructured quantum dots in cultured cells with epifluorescence and transmission electron microscopy

2011 ◽  
Author(s):  
Erin M. Rivera ◽  
Casilda Trujillo Provencio ◽  
Andrea Steinbrueck ◽  
Pawan Rastogi ◽  
Allison Dennis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Cultured Cells ◽  
Transmission Electron

scholarly journals Cells Connected by Tiny Tunnels

2004 ◽  
Vol 12 (5) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wheat Germ ◽  
Cultured Cells ◽  
Cell Communication ◽  
Tunneling Nanotubes ◽  
Pheochromocytoma Cells ◽  
Intracellular Communication ◽  
Transmission Electron ◽  
Multicellular Organisms

Intracellular communication is imperative for multicellular organisms. Such devices as synapses and gap junctions have been recognized for decades. Now Amin Rustom, Raiser Saffrich, Ivanka Markovic, Paul Walther, and Hans-Hermann Gerdes have described a new model of cell-to-cell communication.While looking at PC12 (rat pheochromocytoma) cells in the presence of fluorescently labeled wheat germ agglutinin, Rustom et al. observed relatively long connections extending between cells. These structures were 50 to 200 nm in diameter and up to several cell diameters in length and were named tunneling nanotubes (TNTs). TNTs were subsequently found connecting cultured cells from other lines. They were consistently positioned along the smallest distance between the cells, did not contact the substrate, and occasionally were branched. TNTs immunostained positive for actin, but did not contain microtubules. Scanning and transmission electron microscopy definitively established that a TNT represented a seamless continuity of the plasma membrane from one cell to another.

scholarly journals Fluorescence and electron microscopy to visualize the intracellular fate of nanoparticles for drug delivery

2016 ◽  
Vol 60 (2) ◽  
Author(s):  
M. Costanzo ◽  
F. Carton ◽  
A. Marengo ◽  
G. Berlier ◽  
B. Stella ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drug Delivery ◽  
Transmission Electron Microscopy ◽  
Cultured Cells ◽  
Cell System ◽  
Functional Relationships ◽  
Cell Internalization ◽  
Transmission Electron ◽  
Intracellular Fate

<p>In order to design valid protocols for drug release <em>via</em> nanocarriers, it is essential to know the mechanisms of cell internalization, the interactions with organelles, and the intracellular permanence and degradation of nanoparticles (NPs) as well as the possible cell alteration or damage induced. In the present study, the intracellular fate of liposomes, polymeric NPs and mesoporous silica NPs (MSN) has been investigated in an <em>in vitro</em> cell system by fluorescence and transmission electron microscopy. The tested nanocarriers proved to be characterized by specific interactions with the cell: liposomes enter the cells probably by fusion with the plasma membrane and undergo rapid cytoplasmic degradation; polymeric NPs are internalized by endocytosis, occur in the cytoplasm both enclosed in endosomes and free in the cytosol, and then undergo massive degradation by lysosome action; MSN are internalized by both endocytosis and phagocytosis, and persist in the cytoplasm enclosed in vacuoles. No one of the tested nanocarriers was found to enter the nucleus. The exposure to the different nanocarriers did not increase cell death; only liposomes induced a reduction of cell population after long incubation times, probably due to cell overloading. No subcellular damage was observed to be induced by polymeric NPs and MSN, whereas transmission electron microscopy revealed cytoplasm alterations in liposome-treated cells. This important information on the structural and functional relationships between nanocarriers designed for drug delivery and cultured cells further proves the crucial role of microscopy techniques in nanotechnology.</p>

scholarly journals Reversible embedment cytochemistry (REC): a versatile method for the ultrastructural analysis and affinity labeling of tissue sections.

1986 ◽  
Vol 34 (2) ◽  
pp. 177-188 ◽  
Author(s):  
G Gorbsky ◽  
G G Borisy
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Cell Structure ◽  
Linear Polymers ◽  
Fixed Tissue ◽  
Affinity Labels ◽  
Tissue Sections ◽  
Culture Cells ◽  
Transmission Electron ◽  
Critical Point Drying

Reversible embedment cytochemistry (REC) is a new method for revealing cellular ultrastructure and for improving access of intracellular targets to macromolecular affinity labels. Fully polymerized polymethylmethacrylate was dissolved in dichloromethane and infiltrated into fixed tissue-culture cells and tissues. After evaporation of the solvent, samples were left in hard plastic. Samples were thus embedded without exposure to chemical polymerization reactions that might damage tissue ultrastructure or antigenicity. Glass or diamond knives fitted with water troughs were used to cut sections 30-1000 nm thick. Since polymethylmethacrylate is composed of linear polymers that are not covalently crosslinked, the plastic was easily extracted from the sections by immersion in solvent. Subsequently, various preparative methods, including negative staining, critical point-drying, and platinum-carbon rotary shadowing, were used to provide detailed images of well-preserved cell structure for conventional and high-voltage transmission electron microscopy. Fluorescein-conjugated affinity labels were used to obtain subcellular distributions of target molecules in semi-thick sections of cultured cells and tissues for light microscopy. Colloidal gold-labeled antibodies were used to localize microtubules in sections of cultured cells by electron microscopy. REC is a versatile method that should find wide application in many studies of cellular function.

Ultrastructural Studies Relating to the Surface Morphology of Cultured Cells

1970 ◽  
Vol 6 (2) ◽  
pp. 477-484
Author(s):  
R. G. P. PUGH-HUMPHREYS ◽  
W. SINCLAIR
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Kidney Cells ◽  
Replica Technique ◽  
Regular Feature ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Surface Replica ◽  
Mesenchyme Cells ◽  
Canine Kidney

Scanning electron microscopy and a surface-replica technique for transmission electron microscopy have been used to study the ultrastructural features of cultured-cell surfaces The presence of microvilli measuring 0.1-0.2 µm in diameter by up to 5 µm in length has been noted as a regular feature of Landschütz ascites, ‘fibroblastic’ HeLa, and canine kidney, cells. The surfaces of chick mesenchyme cells were notably almost devoid of microvilli. The presence of microvilli at the cell surface is discussed briefly.

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.

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