Sites of DNA Synthesis in the Mitochondria of Physarum polycephalum as Revealed by Electron Microscopic Autoradiography

1974 ◽  
Keyword(s):  
Dna Synthesis ◽  
Physarum Polycephalum ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography

Simultaneous Electron Microscopic Autoradiographic and Immunocytochemical Localization of H-l Parvovirus DNA Synthesis and Protein Accumulation in Human NB Cells

1977 ◽  
Vol 35 ◽  
pp. 386-387
Author(s):  
Irwin I. Singer ◽  
Solon L. Rhode
Keyword(s):  
Dna Synthesis ◽  
Specific Activity ◽  
High Specific Activity ◽  
Viral Proteins ◽  
Protein Accumulation ◽  
Cell Nuclei ◽  
Electron Microscopic ◽  
Viral Protein Synthesis ◽  
Electron Microscopic Autoradiography ◽  
Conditional Mutant

Fine structural and immunocytochemical experiments have indicated that two distinct categories of H-l viral proteins exhibit different sites of accumu- lation within infected human NB cell nuclei: A), assembled capsids (either “empty” or “full”) are associated with euchromatic fibers; B). unassembled viral proteins accumulate upon heterochromatin (HC) and nucleolar associated chromatin (NAC) (1,2). Since H-l progeny ss DNA synthesis requires viral protein synthesis (3), and presumably host cell enzymes as well, we attempted to localize it with respect to the above sites using electron microscopic autoradiography (EMARG). We studied infections induced by wt H-l, or ts-1 H-l, a conditional mutant defective in progeny ss DNA synthesis at the re- strictive temperature (3). Parasynchronous NB cultures were obtained by methotrexate treatment, infected with wt H-l (at,37°C), or ts-1 H-l (at 39.5°C), and pulsed with high specific activity H-thymidine (100 Ci/mmol) for either 2, 5, 10 or 60 min.

Localization of Gallium-67 in Peritoneal Cells by Electron Microscopic Autoradiography

1973 ◽  
Vol 31 ◽  
pp. 404-405
Author(s):  
D. C. Swartzendruber ◽  
Norma L. Idoyaga-Vargas
Keyword(s):  
Clinical Trials ◽  
Soft Tissue ◽  
Tumor Tissue ◽  
Soft Tissue Tumors ◽  
Clinical Usefulness ◽  
Electron Microscopic ◽  
Normal Cells ◽  
Electron Microscopic Autoradiography ◽  
Peritoneal Cells ◽  
Gallium 67

The radionuclide gallium-67 (67Ga) localizes preferentially but not specifically in many human and experimental soft-tissue tumors. Because of this localization, 67Ga is used in clinical trials to detect humar. cancers by external scintiscanning methods. However, the fact that 67Ga does not localize specifically in tumors requires for its eventual clinical usefulness a fuller understanding of the mechanisms that control its deposition in both malignant and normal cells. We have previously reported that 67Ga localizes in lysosomal-like bodies, notably, although not exclusively, in macrophages of the spocytaneous AKR thymoma. Further studies on the uptake of 67Ga by macrophages are needed to determine whether there are factors related to malignancy that might alter the localization of 67Ga in these cells and thus provide clues to discovering the mechanism of 67Ga localization in tumor tissue.

The deposition of Hg203-chlormerodrin in experimental brain tumors

1971 ◽  
Vol 35 (3) ◽  
pp. 303-308 ◽  
Author(s):  
Tatsuya Kobayashi ◽  
Louis Bakay ◽  
Joseph C. Lee
Keyword(s):  
Brain Tumors ◽  
Tumor Cells ◽  
Normal Brain ◽  
Intracranial Tumors ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Content Type ◽  
Meningeal Tumors ◽  
Vacuolar System ◽  
Fine Print

✓ The deposition of Hg203-chlormerodrin was studied in intracranial tumors in mice induced by implantation of 20-methyl cholanthrene by tissue assay, as well as light microscopic and electron microscopic autoradiography. The investigations were carried out in astrocytomas, glioblastomas, and meningeal tumors. The chlormerodrin content of the tumors exceeded that of normal brain with a significant tumor/brain ratio ranging from 5.8 to 22.5. It was found that the chlormerodrin molecule becomes rapidly incorporated in the tumor cells, with a preference for that portion of the cytoplasm associated with the vacuolar system.

scholarly journals ELECTRON MICROSCOPIC EXAMINATION OF THE SITES OF NUCLEAR RNA SYNTHESIS DURING AMPHIBIAN EMBRYOGENESIS

1965 ◽  
Vol 26 (3) ◽  
pp. 937-958 ◽  
Author(s):  
Shuichi Karasaki
Keyword(s):  
Rna Synthesis ◽  
Developmental Stages ◽  
Early Embryo ◽  
Tail Bud ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Nuclear Rna Synthesis ◽  
Nuclear Rna ◽  
Chromatin Material ◽  
Labeled Rna

The site of H3-uridine incorporation and the fate of labeled RNA during early embryo-genesis of the newt Triturus pyrrhogaster were studied with electron microscopic autoradiography. Isolated ectodermal and mesodermal tissues from the embryos were treated in H3-uridine for 3 hours and cultured in cold solution for various periods before fixation with OsO4 and embedding in Epon. At the blastula stage, the only structural component of the nucleus seen in electron micrographs is a mass of chromatin fibrils. At the early gastrula stage, the primary nucleoli originate as small dense fibrous bodies within the chromatin material. These dense fibrous nucleoli enlarge during successive developmental stages by the acquisition of granular components 150 A in diameter, which form a layer around them. Simultaneously larger granules (300 to 500 A) appear in the chromatin, and they fill the interchromatin spaces by the tail bud stage. Autoradiographic examination has demonstrated that nuclear RNA synthesis takes place in both the nucleolus and the chromatin, with the former consistently showing more label per unit area than the latter. When changes in the distribution pattern of radioactivity were studied 3 to 24 hours after immersion in isotope at each developmental stage, the following results were obtained. Labeled RNA is first localized in the fibrous region of the nucleolus and in the peripheral region of chromatin material. After longer culture in non-radioactive medium, labeled materials also appear in the granular region of the nucleolus and in the interchromatin areas. Further incubation gives labeling in cytoplasm.

Biochemical and morphological characterization of the nuclear matrix during the synchronous cell cycle of Physarum polycephalum

1993 ◽  
Vol 105 (4) ◽  
pp. 1121-1130 ◽  
Author(s):  
S. Lang ◽  
T. Decristoforo ◽  
W. Waitz ◽  
P. Loidl
Keyword(s):  
Cell Cycle ◽  
Nuclear Matrix ◽  
Physarum Polycephalum ◽  
Nuclear Periphery ◽  
S Phase ◽  
Cycle Phase ◽  
Electron Microscopic ◽  
Nuclear Lamins ◽  
Synchronous Cell ◽  
Matrix Bound

We have investigated biochemical and ultrastructural aspects of the nuclear matrix during the naturally synchronous cell cycle of Physarum polycephalum. The morphology of the in situ nuclear matrix exhibited significant cell cycle changes as revealed by electron microscopic examination, especially during the progression of nuclei through mitosis and S-phase. In mitosis the interchromatin matrix was found to be retracted to the nuclear periphery; during S-phase this interchromatin matrix gradually resembled, concomitant with the reconstruction of a nucleolar remnant structure. During the G2-period no significant changes in matrix morphology were observed. The pattern of nuclear matrix proteins was invariant during the cell cycle; no cycle phase-specific proteins could be detected. In vivo labelling of plasmodia with [35S]methionine/cysteine showed that only a few proteins are synthesized and assembled into nuclear matrix structures in a cell cycle-dependent way; the majority of proteins were synthesized almost continuously. This was also shown for nuclear lamins homologues. In contrast to bulk nuclear histones, those histones that remain tightly bound to the nuclear matrix were synthesized and assembled into nuclear structures in the very first hour of S-phase; assembly was terminated in mid-S-phase, indicating that nuclear matrix-bound chromatin is replicated early in S-phase. Comparison of the acetylation pattern of matrix-bound histone H4 with bulk nuclear H4 revealed a largely elevated acetate content of matrix H4. The percentage of acetylated subspecies was entirely different from that in bulk nuclear H4, indicating that matrix-associated histones represent a subpopulation of nuclear histones with distinct properties, reflecting specific structural requirements of matrix-attached chromatin.

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