scholarly journals RESOLUTION IN AUTORADIOGRAPHY USING SEMITHIN SECTIONS

1974 ◽  
Vol 22 (4) ◽  
pp. 217-222 ◽  
Author(s):  
MIRIAM M. SALPETER ◽  
G. C. BUDD ◽  
SHARON MATTIMOE
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Line Source ◽  
Light Microscope ◽  
Electron Microscope Autoradiography ◽  
Density Distributions ◽  
Microscope Autoradiography ◽  
Semithin Sections ◽  
Tritium Labeling

Resolution studies were performed on light microscope autoradiographic specimens of 0.5-1 µ thicknesses coated with Ilford L4 and Kodak NTB2 and AR10 emulsions. A radioactive line source, previously employed for electron microscope autoradiography (Salpeter, Bachmann and Salpeter, 1969; Salpeter and Salpeter, 1971), was used. It was found that with tritium labeling the half-distance (HD) was approximately 3500 Å. This value was not significantly altered with increasing section beyond 0.5 µ or emulsion thickness beyond ~2,000 Å. A 0.5-µ section labeled with 14C had an HD value of 7000 Å when coated with a monolayer of Ilford L4 or Kodak NTB2 emulsion. Increasing section or emulsion thickness did increase this value. It was found that the density distributions, normalized in units of their own HD, gave a good fit to the set of universal curves derived from electron microscope autoradiographic specimens. These universal curves are thus applicable for analyzing light microscope autoradiographic specimens. Some tritium HD values applicable to high voltage microscopy are also given.

scholarly journals CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS

1964 ◽  
Vol 22 (3) ◽  
pp. 505-513 ◽  
Author(s):  
D. R. Wolstenholme ◽  
W. Plaut
Keyword(s):  
Electron Microscope ◽  
Dna Synthesis ◽  
Light Microscope ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Electron Microscope Autoradiography ◽  
Cytoplasmic Dna ◽  
Microscope Autoradiography ◽  
Normal Particle ◽  
Labeling Pattern

The application of electron microscope autoradiography to Amoeba proteus cells labeled with tritiated thymidine has permitted the identification of morphologically distinct particles in the cytoplasm as the sites of incorporated DNA precursor. The particles correspond to those previously described from light microscope studies, with respect to both H3Tdr incorporation and distribution in centrifugally stratified amoebae. Ingested bacteria differ from the particles, in morphology as well as in the absence of associated label. Attempts to introduce a normal particle labeling pattern by incubating amoebae with labeled sediment derived from used amoeba medium failed. The resultant conclusion, that the particles are maintained in the amoeba by self-duplication, is supported by the presence of particles in configurations suggestive of division.

Incorporation of Cholesterol into Peripheral Nerve Myelin

1972 ◽  
Vol 30 ◽  
pp. 334-335
Author(s):  
Frank A. Rawlins
Keyword(s):  
Electron Microscope ◽  
Sciatic Nerve ◽  
Electron Microscope Autoradiography ◽  
Myelin Sheaths ◽  
Microscope Autoradiography ◽  
Grain Distribution ◽  
Sciatic Nerves ◽  
Autoradiographic Analysis ◽  
Old Mice ◽  
Short Times

Several speculations exist as to the site of incorporation of preformed molecules into myelin. The possibility that an autoradiographic analysis of cholesterol-1,2-H3 incorporation at very short times after injection might shed some light in the solution of that problem led to the present experiment.Cholesterol-1,2-H3 was injected intraperitoneally into 24 tenday old mice. The animals were then sacrificed at 10,20,30,40,60,90,120 and 180 min after the injection and the sciatic nerves were processed for electron microscope autoradiography. To analyze the grain distribution in the autoradiograms of cross and longitudinal sections from each sciatic nerve myelin sheaths were subdivided into three compartments named: outer 1/3, middle 1/3 and inner 1/3 compartments.It was found that twenty min. after the injection of cholesterol -1.2-H3 (Figs. 1 and 2), 55% of the total number of grains (t.n.g) found in myelin were within the outer 1/3 compartment, 9% were within the middle 1/3 and 36% within the inner 1/3 compartment

Synthesis and Localization of Sulphated Mucopolysaccharide in Megakaryocytes and Platelets of the Rat, An Analysis by Electron-Microscope Autoradiography

1972 ◽  
Vol 10 (3) ◽  
pp. 705-717
Author(s):  
G. G. MacPHERSON
Keyword(s):  
Electron Microscope ◽  
Golgi Apparatus ◽  
Blood Platelets ◽  
Total Activity ◽  
Electron Microscope Autoradiography ◽  
Dense Granules ◽  
Level Of Activity ◽  
Microscope Autoradiography ◽  
Almost All

Electron-microscope autoradiography has been used to investigate the synthesis and localization of sulphated mucopolysaccharide in megakaryocytes and blood platelets. Following 10-min incubation of bone marrow with 35S-sulpahte in vitro the majority of the activity in megakaryocytes was associated with the Golgi apparatus, but a substantial proportion was associated with other cytoplasmic organelles, suggesting either rapid transport or sulphation of mucopolysaccharide outside the Golgi apparatus. Three hours after the intravenous injection of 35SO4 only a small proportion of the total activity was associated with the Golgi apparatus, most being associated with demarcation membranes and dense granules, while 12 h after injection almost all the activity was associated with demarcation membranes and granules. A rising proportion of activity localized solely on the demarcation membranes suggested that they may possess some activity of their own. Autoradiographs of blood platelets prepared 72 h after the injection of 35SO4 were analysed. It was shown that most of the activity was associated with the α-granules, but there was strong evidence that the platelet membrane possessed a low level of activity.

Timing of nucleolar DNA replication in Amoeba proteus

1976 ◽  
Vol 22 (3) ◽  
pp. 521-530
Author(s):  
I. Minassian ◽  
L.G. Bell
Keyword(s):  
Electron Microscope ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Central Region ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Electron Microscope Autoradiography ◽  
Microscope Autoradiography ◽  
G2 Phase

Light- and electron-microscope autoradiography have been used to follow the incorporation of [3H]thymidine at different stages during the interphase of synchronously growing populations of Amoeba proteus. Two main patterns were found for tritiated thymidine incorporation, i.e. DNA synthesis. The major incorporation was in the central region of the nucleus, but a lesser degree of incorporation occurred in the nucleolar region. The bulk of this nucleolar DNA was found to be late replicating, i.e. it replicated during the G2 phase.

Studies on the Synthesis and Composition of Extracellular Mucilage in the Unicellular Red Alga Rhodella

1974 ◽  
Vol 16 (1) ◽  
pp. 1-21
Author(s):  
L. V. EVANS ◽  
MAUREEN E. CALLOW ◽  
ELIZABETH PERCIVAL ◽  
V. FAREED
Keyword(s):  
Electron Microscope ◽  
Uronic Acid ◽  
Red Alga ◽  
Electron Microscope Autoradiography ◽  
Golgi Bodies ◽  
Microscope Autoradiography ◽  
Reducing Substances

35SO42- has been used to investigate the production of extracellular mucilage by log-phase cells. Uptake of isotope occurs most rapidly in the light, when cells are actively dividing. The mucilage comprises about 50% carbohydrate, 16% protein and 10% sulphate. The major sugar is xylose; uronic acid, a small amount of galactose, glucose (trace) and 2 reducing substances are also present. Methylation studies have established the major linkages. Electron-microscope autoradiography shows that the mucilage is packaged in the Golgi bodies, passing to the plasmalemma in large vesicles. Sulphation of the mucilage occurs in the Golgi cisternae.

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