scholarly journals DETECTION OF DNA BY TRITIATED ACTINOMYCIN D ON ULTRATHIN FROZEN SECTIONS

1972 ◽  
Vol 53 (3) ◽  
pp. 798-808 ◽  
Author(s):  
Roch Bernier ◽  
Roberto Iglesias ◽  
René Simard

Ultrathin frozen sections of fresh liver tissue were floated on actinomycin D-3H. Quantitative high resolution radioautography was performed to determine the value of the method for detection of DNA by electron microscopy. A complete series of control experiments involving various treatments of frozen sections with enzymes (pronase, DNase) and 0.1 N HCl were also carried out to determine the specificity of the labeling. The results indicate the value of the method for detection of DNA directly on ultrathin frozen sections. Short treatments with pronase followed by DNase reduce the labeling to zero, whereas removal of chromosomal proteins with HCl increases the amount of radioactivity in the nucleus considerably. The results are discussed in view of the future applications opened by ultracryotomy, since radioautographic detection of various macromolecules and cellular components by labeled compound with specific affinities will now be possible.

1995 ◽  
Vol 1 (5) ◽  
pp. 217-230
Author(s):  
A. Kent Christensen ◽  
Terry B. Lowry

Ethanol (ethyl alcohol) has long been a standard reagent used in preparing tissues for light and electron microscopy. After fixation, tissues are usually dehydrated with ethanol before being embedded in paraffin or plastic. In this study we show that the ethanol-infiltrated tissue can be frozen and sectioned directly without embedding. When tissue impregnated with ethanol is cooled below about −117°C with liquid nitrogen, the ethanol solidifies without appreciable crystallization. The frozen tissue can then be sectioned in a commercial cryoultramicrotome that is set at −155 to −170°C to produce semithin frozen sections (0.5 to 3 μm thick) for light microscopy or ultrathin frozen sections (50 to 100 nm thick) for electron microscopy. Sections are picked up and mounted on glass slides or EM grids by means that are in current use for ice ultrathin frozen sectioning. Because there is no apparent freezing damage, the morphology in these ethanol frozen sections of unembedded tissue appears generally quite good, often resembling that obtained by conventional EM techniques. Examples are provided that illustrate the use of this material for immunocytochemistry at the light and electron microscope levels.


Author(s):  
K. T. Tokuyasu ◽  
J. Slot ◽  
S. J. Singer

Immunofluorescent microscopy is more suitable for the analysis of a large number of cells, often greater in the sensitivity for the detection of antigens, and more readily applicable for the identification of multiple antigens than immunoe1ectron microscopy. For combining these features of fluorescent microscopy with the superior resolution of electron microscopy, we attempted to observe the same immunolabeled ultrathin frozen sections with both light and electron microscopy.Ultrathin frozen sections of rat pancreas fixed in a mixture of 2% formaldehyde and 0.2% g1utaraldehyde for 1 hr at 4°C were first immunostained with rabbit anti-rat amylase antibodies, then very lightly with ferritin-goat anti-rabbit IgG conjugates and heavily with rhodamine-goat anti-rabbit IgG conjugates. For light microscopic observation, grids were suspended underneath the cover glass with a very thin layer of 50-90% glycerol and the cover glass was separated from the slide glass by a spacer to avoid the contact of the grid with the slide glass. After the light microscope observation, the grids were floated on 0.1 M phosphate buffer by dissolving glycerol into the buffer and processed for electron microscopy.


Author(s):  
K. T. Tokuyasu

The successful routine use of cryoultramicrotomy to examine ultrathin sections by transmission electron microscopy requires the application of suitable staining to delineate the ultrastructure. While negative staining is quite effective for certain purposes1, 2, positive staining is more appropriate for immunocytochemical studies because it does not obscure the immunolabels.


1986 ◽  
Vol 34 (4) ◽  
pp. 491-500 ◽  
Author(s):  
M R Celio ◽  
G A Keller ◽  
F E Bloom

We have utilized immunocryoultramicrotomy to detect synapsin, somatostatin, parvalbumin, and tubulin at the ultrastructural level. Immunocryoultramicrotomy combines informative identification of morphology with accurate immunolabeling. Moreover, since no detergents or organic solvents are used to enable antibody penetration, and since no enzyme marker diffusion occurs, localization of the antigens should be more accurate. Accordingly, it was possible to localize precisely all four antigens within a well-preserved structure. Application of this method has important advantages for high-resolution localization of molecules relevant to neuronal function.


Author(s):  
A. Kent Christensen

In the mid-1960s, while on the faculty of the Anatomy Department at Stanford, I was particularly interested in the cell biology of steroid-secreting cells. I had studied the ultrastructure of these cells, and was anxious to trace the pathways of steroid hormone synthesis and of the secretion from the cell. An invitation to speak at an international steroid congress in Milan, Italy, in May 1966, afforded me an opportunity to travel in Europe before the meeting started. During that trip I had a very enjoyable visit with Dr. Wilhelm Bernhard, in the Paris suburb Villejuif. He had developed means of cutting ultrathin frozen sections (UFS) of fixed tissue on a Sorvall MT-1 ultramicrotome maintained in a freezer at about −35°C. As the sections were cut, they floated off on a solution of dimethyl sulfoxide and water, from which they were picked up on EM grids, treated for cytochemistry, stained with uranyl acetate, and then viewed by EM.


1971 ◽  
Vol 49 (3) ◽  
pp. 731-746 ◽  
Author(s):  
W. Bernhard ◽  
Annie Viron

Ultrathin frozen sections of biological tissues for electron microscopy provide certain advantages in cytochemical studies in which the penetration of cells by large molecules is necessary and in morphological studies of cellular constituents which are dissolved by the reagents employed in routine plastic embedding. The recent introduction of several types of commercially available cryo-ultramicrotomes makes it possible for many laboratories to employ this valuable tool. This paper summarizes recent improvements in the methods developed in this laboratory for preparing ultrathin frozen sections and reviews some of the inherent problems involved in their use. These procedures may serve as a baseline for other investigators who can then modify or adapt them for their specific purposes.


1967 ◽  
Vol 34 (3) ◽  
pp. 757-771 ◽  
Author(s):  
W. Bernhard ◽  
Elizabeth H. Leduc

A relatively simple method for obtaining ultrathin, frozen sections for electron microscopy has been developed. Tissues, cultured cells, and bacteria may be employed. They are fixed in 1.25–4% glutaraldehyde for 1–4 hr, are washed overnight in buffer at 3°C, and are embedded in 20% thiolated gelatin or pure gelatin. Before sectioning they are partially dehydrated in 50% glycerol, frozen in liquid nitrogen on a modified tissue holder, and subsequently maintained at -70°C with dry ice. Finally, they are sectioned very rapidly with glass knives on a slightly modified Porter-Blum MT-1 microtome in a commercial deep-freeze maintained at -35°C and are floated in the trough of the knife on a 40% solution of dimethylsulfoxide (DMSO). The sections are picked up in plastic loops and transferred to distilled water at room temperature for thawing and removal of the DMSO, placed on grids coated with Formvar and carbon, air-dried, and stained with phosphotungstic acid, sodium silicotungstate, or a triple stain of osmium tetroxide, uranyl acetate, and lead. Large flat sections are obtained in which ultrastructural preservation is good. They are particularly useful for cytochemical studies.


1991 ◽  
Vol 100 (1) ◽  
pp. 227-236
Author(s):  
I. Sabanay ◽  
T. Arad ◽  
S. Weiner ◽  
B. Geiger

We describe the development and application of a novel approach to high-resolution ultrastructural analysis of cells and tissues. It is based on the preparation of ultrathin frozen sections of fixed tissues, rinsing of the sections, followed by their embedding on the grid in a layer of vitrified ice, and direct observation with a cryoelectron microscope. Examination of smooth muscle, kidney and heart tissues showed that although no heavy metal staining was used, high-contrast images are obtained. Fine details of cytoplasmic filaments and organelles, membranes and membrane-associated structures, as well as connective-tissue elements are all visible. The new method is suitable for immunolabeling, including high resolution localization of specific molecules within the cytoplasm.


1968 ◽  
Vol 128 (2) ◽  
pp. 357-373 ◽  
Author(s):  
William L. Kopp ◽  
Jerry S. Trier ◽  
Iain L. Mackenzie ◽  
Robert M. Donaldson

Antibodies (AbMVM) were produced in rabbits to microvillous membranes isolated from hamster small bowel. Incubation of frozen sections of hamster small bowel with fluorescein-labeled AbMVM showed specific reaction with brush borders, but not with other intestinal cellular components. Electron microscopy with ferritin-conjugated AbMVM localized the antigens more precisely to the surface mucopolysaccharide coat of the brush borders. AbMVM also reacted with the brush border of colon and of proximal renal tubules of hamsters but not with those of hamster stomach or gall bladder. It also reacted with the brush borders of some rat and human tissues, but not with those of rabbits. In addition, fluorescent-labeled AbMVM combined specifically with cell walls of some yeasts, but not of several bacteria. AbMVM also contained a weak precipitin to a component of hamster serum, which migrated like prealbumin in immunoelectrophoresis.


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