Incorporation of tritiated cytochalasin B into ectodermal explants of the amphibian gastrula

Development ◽  
1976 ◽  
Vol 36 (1) ◽  
pp. 209-223
Author(s):  
M. M. Perry ◽  
G. G. Selman ◽  
J. Jacob
Keyword(s):  
Cytochalasin B ◽  
Superficial Layer ◽  
Electron Microscopic ◽  
Cytoplasmic Matrix ◽  
Electron Microscopic Autoradiography ◽  
Triturus Alpestris ◽  
Cell Fractions ◽  
Cellular Components ◽  
Silver Grains ◽  
Compact Spheres

Ectodermal explants from gastrulae of Triturus alpestris were exposed to tritiated cytochalasin B (5 and 10µg/ml) for ½–2½ h. The flat explants failed to heal into compact spheres and the component cells gradually rounded up. Radioactivity in the fixed and sectioned material was analysed by light and electron microscopic autoradiography. Silver grains were found predominantly over the yolk platelets, but were also scattered over other cellular components. Areas containing pigment granules or the feltwork material, present in the apices of dissociating cells of the superficial layer, exhibited higher activity than areas containing mitochondria or cytoplasmic matrix. Lipid droplets and nuclei showed comparatively little activity. The results are discussed in relation to previous findings on the uptake of tritiated cytochalasin D by cell fractions.

RENAL UPTAKE AND METABOLISM OF ADRENOCORTICOTROPHIN ANALOGUES IN THE RAT: AN AUTORADIOGRAPHIC STUDY

1977 ◽  
Vol 74 (1) ◽  
pp. 23-35 ◽  
Author(s):  
J. R. J. BAKER ◽  
H. P. J. BENNETT ◽  
R. A. CHRISTIAN ◽  
C. McMARTIN
Keyword(s):  
Autoradiographic Study ◽  
Proximal Tubules ◽  
Tyrosine Residue ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Renal Uptake ◽  
Endocytotic Vesicles ◽  
Silver Grains ◽  
Uptake And Metabolism

Renal resorption of tritiated adrenocorticotrophin analogues was studied in the rat using light microscopic and quantitative electron microscopic autoradiography. The synthetic corticotrophins used were Synacthen (corticotrophin-(1–24)-tetracosapeptide) and C 41795-Ba ([D-Ser1,Lys17,Lys18]-corticotrophin-(1–18)-octadecapeptide amide), the tetracosapeptide being tritiated in either the tyrosine residue of position 2 or 23 or the phenylalanine of position 7 and the octadecapeptide in the tyrosine of position 2. Inspection of autoradiographs showed that peptides injected intravenously were resorbed into proximal tubules by endocytosis to produce vesicles whose radiolabel later appeared in lysosomes, a route previously elucidated for other peptides and proteins. The use of two techniques for analysis of electron microscopic autoradiographs, however, suggested that apical tubules also acquire label and are in some way involved in the transfer of resorbed labelled material from endocytotic vesicles to lysosomes. In addition, the autoradiographic analyses revealed that the duration of lysosomal labelling depends upon the position of tritium in the chain. Thus, when the CO2H-terminus of Synacthen was labelled, silver grains were more transiently associated with lysosomes than was the case when the NH2-terminal or core regions were tritiated, indicating a greater resistance of these portions of the peptide to attack by intracellular peptidase. The label from the chemically protected C 41795-Ba was also less readily expelled from the lysosomes of the proximal tubules.

Sulfated proteoglycan accumulation during development of the embryonic chick limb bud studied by electron microscopic autoradiography

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 195-209
Author(s):  
Moira Cioffi ◽  
Robert L. Searls ◽  
S. Robert Hilfer
Keyword(s):  
Extracellular Space ◽  
Limb Bud ◽  
Proteoglycan Synthesis ◽  
High Concentration ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Intracellular Space ◽  
Muscle Region ◽  
Significant Difference ◽  
Silver Grains

Cartilage cells are characterized by a high concentration of extracellular sulfated proteoglycan. Electron microscopic autoradiography was used to compare the incorporation of sulfate into proteoglycan by limb-bud chondrogenic and myogenic cells. From stage 19 to stage 21 there was no significant difference between the cartilage- and muscle-forming regions in the number of silver grains over either the extracellular space or the intracellular space. From stage 22 to 25 the number of extracellular silver grains was significantly greater in the chondrogenic region than in the myogenic region, but the number of intracellular silver grains was the same. Since most of the silver grains were intracellular, no significant difference in the total number of grains was found between the two tissues. Stage-26 and -27 embryos showed a significantly greater number of silver grains over both the cells and the extracellular space in the cartilage region than in the muscle region. Thus, the first step of cartilage differentiation involves a decrease in the extracellular deposition of sulfated proteoglycan in the myogenic region rather than an increase in deposition in the chondrogenic region between stage 22 and 25. After stage 25 there is an increase in sulfated proteoglycan synthesis in the chondrogenic region relative to the myogenic region.

scholarly journals THE UPTAKE AND DEVELOPMENT OF VACCINIA VIRUS IN STRAIN L CELLS FOLLOWED WITH LABELED VIRAL DEOXYRIBONUCLEIC ACID

1963 ◽  
Vol 18 (1) ◽  
pp. 51-72 ◽  
Author(s):  
Samuel Dales
Keyword(s):  
Cell Membrane ◽  
Vaccinia Virus ◽  
Deoxyribonucleic Acid ◽  
Progeny Virus ◽  
Electron Microscopic ◽  
Outer Coat ◽  
Cytoplasmic Matrix ◽  
Electron Microscopic Autoradiography ◽  
L Cells ◽  
Virus Core

Vaccinia virus which had its DNA labeled with thymidine-H3 was purified and used as inoculum for L cells growing in suspension. Samples taken over an 8-hour period after infection were studied by light and electron microscopic autoradiography. Within 20 minutes of its being taken up at the cell membrane in phagocytic vesicles, the outer coat of vaccinia becomes disrupted and the virus core containing the labeled DNA passes into the cytoplasmic matrix. Within 1 hour after inoculation the labeled material passes out of the cores into zones of viroplasm, where cores or remnants of cores are gathered and the label becomes more concentrated by 3 hours after inoculation. Most of the label is conserved in the viroplasm areas during the remainder of the experiment. However, 6 hours after inoculation a very small proportion of progeny virus in the cytoplasm, morphologically distinct from the cores of the inoculum, has associated with it labeled material, perhaps derived from the DNA of the inoculum.

scholarly journals Nuclear and Extranuclear Estrogen Binding Sites in the Rat Forebrain and Autonomic Medullary Areas

Endocrinology ◽  
2008 ◽  
Vol 149 (7) ◽  
pp. 3306-3312 ◽  
Author(s):  
Teresa A. Milner ◽  
Laura S. Lubbers ◽  
Stephen E. Alves ◽  
Bruce S. McEwen
Keyword(s):  
Subcellular Location ◽  
Brain Regions ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Solitary Tract ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Ca1 Region ◽  
Rat Forebrain ◽  
Silver Grains

Immunocytochemical studies have shown that nuclear and extranuclear estrogen receptors (ERs) are present in several extrahypothalamic brain regions. The goal of this study was to determine the subcellular location of functional ERs, particularly extranuclear ERs, by demonstrating 125I-estradiol binding in the rat forebrain and medullary sections prepared for light and electron microscopic autoradiography. Some sections were immunocytochemically labeled with the catecholamine-synthesizing enzyme, tyrosine hydroxylase (TH), prior to the autoradiographic procedure. By light microscopy, dense accumulations of silver grains denoting 125I-estradiol binding were observed over cells in the ventromedial and arcuate hypothalamic nuclei, amygdala, and nucleus of the solitary tract. In sections labeled for TH, large accumulations of silver grains were admixed with TH-labeled processes in the medial nucleus of the amygdala and over TH-labeled perikarya in the medial and commissural nucleus of the solitary tract. Electron microscopic analyses were focused on the rostral ventrolateral medulla and the hippocampal CA1 region, two regions previously shown to have extranuclear ERs. In the rostral ventrolateral medulla, silver grains indicative of 125I-estradiol binding were found within a few large terminals, affiliated with mitochondria. In the hippocampus, autoradiographic silver grains denoting 125I-estradiol binding were associated with mitochondria in dendritic shafts or were near synaptic specializations on dendritic spines. These patterns of silver grain labeling were not seen in sections from rats that received 125I-estradiol combined with cold estradiol. The association of 125I-estradiol binding with pre- and postsynaptic profiles supports a functional role for nonnuclear ERs in brain.

45Calcium localization in islets of Langerhans, a study by electron-microscopic autoradiography

1976 ◽  
Vol 21 (2) ◽  
pp. 415-422
Author(s):  
S.L. Howell ◽  
M. Tyhurst
Keyword(s):  
B Cells ◽  
Islets Of Langerhans ◽  
Dominant Role ◽  
Cytosolic Calcium ◽  
High Energy ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Pancreatic B Cells ◽  
Storage Granules ◽  
Silver Grains

Attempts were made to localize the sites of uptake of 45calcium in B cells of islets of Langerhans by electron-microscopic autoradiography. Despite the potential sources of error inherent in the partial loss of radioactivity during fixation, and in the relatively high energy of emission of this isotope, distribution of silver grains differed signficantly from random in all experiments. Grains were concentrated over mitochondria and to a lesser extent over storage granules. Incubation of islets in the presence of 10 mM glucose and isobutylmethyl-xanthine before fixation and autoradiography resulted in a small but not statistically significant reduction in silver grains associated with the mitochondria. These results further indicate a dominant role of mitochondria in the regulation of cytosolic calcium concentrations in pancreatic B cells.

scholarly journals A STUDY OF THE ULTRASTRUCTURAL LOCALIZATION OF HAIR KERATIN SYNTHESIS UTILIZING ELECTRON MICROSCOPIC AUTORADIOGRAPHY IN A MAGNETIC FIELD

1964 ◽  
Vol 21 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Takashi Nakai
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Ultrastructural Localization ◽  
Hair Follicles ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Root Sheath ◽  
Inner Root Sheath ◽  
Anagen Hair ◽  
Cellular Components

The sites of the incorporation of labeled cystine into keratinizing structures were studied in electron microscopic autoradiographs. The tracer used was cystine labeled with S35 emitting long-range ionizing particles. During exposure for 1 to 2 months, according to our method of electron microscopic autoradiography, emulsion-coated specimens were exposed to a static magnetic field which appeared to result in a marked increase in the number of reacted silver grains. In young Swiss mice receiving intraperitoneal injections at 1, 3, and 6 hours before biopsy, conventional autoradiography demonstrated that S35-cystine was intensely localized in the keratogenous zone of anagen hair follicles, and that the radioactivity there increased in intensity progressively with time while the radioactivity in the hair bulb always remained very low. Our observations with electron microscopic autoradiography in a magnetic field appeared to indicate that at 3 and 6 hours after injection the S35-cystine was directly and specifically incorporated into tonofibrils in the hair cortex and into amorphous keratin granules of the hair cuticle layer, possibly without any particular concentration of this substance in the other cellular components. There seemed to be an appreciable concentration of cystine in tonofibrils of the cuticle of the inner root sheath. However, trichohyalin granules in the hair medulla and inner root sheath failed to show any evidence of cystine concentration. The improved sensitivity of the electron microscopic autoradiography with S35-cystine appeared to be partly due to the application of a static magnetic field. However, the reason for this could not be explained theoretically.

scholarly journals Synthesis of CDP-diacylglycerol by rat liver rough microsomes as visualized by electron microscopic autoradiography: relationship to GTP-stimulated membrane fusion.

1991 ◽  
Vol 39 (3) ◽  
pp. 363-372 ◽  
Author(s):  
M Jolicoeur ◽  
F W Kan ◽  
J Paiement
Keyword(s):  
Membrane Fusion ◽  
Rat Liver ◽  
Freeze Fracture ◽  
Phospholipid Metabolism ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography ◽  
Autoradiographic Analysis ◽  
Freeze Fracture Electron Microscopy ◽  
Layer Chromatography ◽  
Silver Grains

Using detergent-free conditions of incubation for the analysis of liponucleotide synthesis, we compared GTP-dependent formation of CDP-diacylglycerol (CDP-DG) and membrane fusion in RNA-depleted rough microsomes from rat liver. After incubation of stripped rough microsomes (SRM) in the presence of GTP and [5-3H]-CTP, radioactivity was recovered in lipid extracts and identified by thin-layer chromatography as a single spot which co-migrated with CDP-DG. The nucleotide requirement for CDP-DG synthesis and that for membrane fusion were observed to be identical. We next carried out an electron microscopic autoradiographic analysis on incubated membranes to determine the site of incorporation of [5-3H]-CTP. Silver grains were observed directly over the unilamellar membranes of natural vesicles. In confirmation of the biochemical data, quantitation of silver grain density indicated more grains over membranes incubated in the presence of GTP than over those incubated in the absence of this nucleotide. For membranes incubated in the presence of GTP, the grain density was similar over fused and unfused membranes in the same preparation. When SRM were incubated with the enzyme co-factors required for synthesis of phosphatidylinositol, a GTP-independent membrane fusion was observed by both transmission and freeze-fracture electron microscopy. Together with the biochemical and autoradiographic data, this suggests that phospholipid metabolism may be activated by GTP and lead to the fusion of RER membrane.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

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.

Distribution of newly formed hepatic glycogen in adrenalectomized rats as observed by radioautography after injection of 3H-galactose

1984 ◽  
Vol 42 ◽  
pp. 228-229
Author(s):  
J. E. Michaels ◽  
J. T. Hung ◽  
E. L. Cardell ◽  
R. R. Cardell
Keyword(s):  
Glycogen Synthesis ◽  
Hepatic Glycogen ◽  
Electron Microscopic ◽  
Routine Procedures ◽  
Silver Grains ◽  
Synthetic Glucocorticoid ◽  
Adrenalectomized Rats

In order to study early events of glycogen synthesis, we have used adrenalectomized (ADX) rats fasted overnight and injected with the synthetic glucocorticoid dexamethasone (DEX) to stimulate glycogen synthesis. Rats were given DEX 0-5 hr prior to sacrifice and injected with 2 mCi 3H-galactose 1 hr prior to sacrifice. Liver was prepared for light (LM) and electron microscopic (EM) radioautography by routine procedures.The concentration of silver grains over hepatic cytoplasm was measured in LM radioautographs using a Zeiss Videoplan. The hepatocytes were categorized as unlabeled if no silver grains (gr) were present, lightly labeled (<10gr/100 μm2 cytoplasm) or intensely labeled (>10 gr/1002 μm cytoplasm). Although very few hepatocytes showed heavy labeling after 1 hr treatment with DEX, by 2 hr after DEX treatment 8% of the cells distributed throughout the lobule were intensely labeled.

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