scholarly journals Appendix: Radioautographic localization of labelled proteins after incubation of guinea-pig islets of Langerhans with [3H]tryptophan

1974 ◽  
Vol 140 (1) ◽  
pp. 22-23 ◽  
Author(s):  
S. L. Howell ◽  
C. Hellerström ◽  
M. Whitfield
Keyword(s):  
B Cells ◽  
Guinea Pig ◽  
B Cell ◽  
Islets Of Langerhans ◽  
Electron Microscopic ◽  
Storage Granules ◽  
Silver Grains ◽  
Electron Microscopic Radioautography ◽  
Significant Concentration

An analysis was made by electron-microscopic radioautography of the distribution of silver grains over storage granules of A2 and B cells after incubation of isolated guinea-pig islets of Langerhans for 17h in the presence of [3H]tryptophan. A significant concentration of labelled proteins was present in the A2 cell, but not in the B-cell granules.

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.

Calcium distribution in islets of Langerhans: a study of calcium concentrations and of calcium accumulation in B cell organelles

1975 ◽  
Vol 19 (2) ◽  
pp. 395-409
Author(s):  
S.L. Howell ◽  
W. Montague ◽  
M. Tyhurst
Keyword(s):  
Endoplasmic Reticulum ◽  
Cyclic Amp ◽  
B Cell ◽  
Islets Of Langerhans ◽  
Cyclic Gmp ◽  
Cell Organelles ◽  
Calcium Accumulation ◽  
Labile Pool ◽  
Storage Granules ◽  
Rat Islets Of Langerhans

Calcium concentrations of various pancreatic B cell organelles have been determined by X-ray microanalysis of areas of frozen sections of unfixed rat islets of Langerhans. Highest concentrations were detected in storage granules and in mitochondria, although calcium was also present in nuclei, in areas of endoplasmic reticulum and of cytoplasm. Accumulation of 45Ca by isolated organelles has been studied in homogenates and isolated subcellular fractions of rat islets of Langerhans. In the presence of a permeant anion (oxalate or phosphate), accumulation of 45Ca into mitochondria and microsomes was strongly stimulated by ATP. This net uptake was diminished during incubation of homogenates or of a mitochondria plus storage granule-rich fraction in the presence of cyclic AMP, dibutyryl cyclic GMP; 2:4-dinitrophenol or of ruthenium red. Investigations of the characteristics of 45Ca accumulation by homogenates prepared from storage granule-depleted islets showed no differences from those of normal islets, suggesting that the granules do not represent an important labile pool of calcium. With the exception of cyclic AMP and cyclic GMP none of the insulin secretagogues tested (glucose, leucine, arginine, adrenalin, noradrenalin, theophylline, glibenclamide) altered calcium accumulation by islet homogenates. On the basis of absolute calcium levels and of 45Ca uptake studies it is concluded that islet B cells contain a readily exchangeable mitochondrial calcium pool, and an endoplasmic reticulum pool containing a lower concentration of calcium which is also readily exchangeable. The storage granules, despite their high calcium content, do not appear to constitute a labile pool. It seems likely that the labile mitochondria and endoplasmic reticulum pools play a predominant role in the regulation of cytoplasmic free calcium levels, which may in turn be important in the regulation of rates of insulin secretion.

scholarly journals LIGHT AND ELECTRON MICROSCOPIC RADIOAUTOGRAPHY OF HEPATIC CELL NUCLEOLI IN MICE TREATED WITH ACTINOMYCIN D

1967 ◽  
Vol 33 (3) ◽  
pp. 489-496 ◽  
Author(s):  
J. C. H. de Man ◽  
N. J. A. Noorduyn
Keyword(s):  
Orotic Acid ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Electron Microscopic ◽  
Granular Component ◽  
Hepatic Cells ◽  
Progressive Loss ◽  
Nucleolar Rna ◽  
Silver Grains ◽  
Electron Microscopic Radioautography

Nucleolar partition induced by actinomycin D was used to demonstrate some aspects of nucleolar RNA synthesis and release in mouse hepatic cells, with light and electron microscopic radioautography. The effect of the drug on RNA synthesis and nucleolar morphology was studied when actinomycin D treatment preceded labeling with tritiated orotic acid. Nucleolar partition, consisting of a segegration into granular and fibrillar parts was visible if a dosage of 25 µg of actinomycin D was used, but nucleolar RNA was still synthesized. After a dosage of 400 µg of actinomycin D, nucleolar RNA synthesis was completely stopped If labeling with tritiated orotic acid preceded treatment with 400 µg of actinomycin D, labeled nucleolar RNA was present 15 min after actinomycin D treatment while high resolution radioautography showed an association of silver grains with the granular component. At 30 min after actinomicyn D treatment all labeling was lost. Since labeling was associated with the granular component the progressive loss of label as a result of actinomycin D treatment indicated a release of nucleolar granules. The correlation between this release and the loss of 28S RNA from actinomycin D treated nucleoli as described in the literature is discussed.

scholarly journals LA SYNTHÈSE DE L'ADN MITOCHONDRIAL CHEZ TETRAHYMENA PYRIFORMIS

1968 ◽  
Vol 39 (2) ◽  
pp. 369-381 ◽  
Author(s):  
Renée Charret ◽  
Jean André
Keyword(s):  
Mitochondrial Dna ◽  
Great Majority ◽  
Tetrahymena Pyriformis ◽  
Logarithmic Phase ◽  
Time Interval ◽  
Electron Microscopic ◽  
Mitochondrial Population ◽  
A Cell ◽  
Silver Grains ◽  
Electron Microscopic Radioautography

Electron microscopic radioautography has been used to study the synthesis of mitochondrial DNA after incorporation of thymidine-3H by cultures in logarithmic phase of Tetrahymena pyriformis during periods ranging from 15 min to 12 hr. The great majority of silver grains are distributed over the macronuclei, the micronuclei, and the mitochondria. The intensity of the label over the entire mitochondrial population is a function of the length of the incubation period within the time interval considered. The intensity of the mitochondrial label was compared with that of the nuclear label. Mitochondria incorporate at the same rate whether the nuclei are synthesizing or not. This persistence of mitochondrial incorporation in the absence of nuclear incorporation excludes the hypothesis of a nuclear origin for mitochondrial DNA. We are not able to determine whether the apparent continuity of synthesis in the entire mitochondrial population of a cell actually represents a series of asynchronous discontinuities.

Preparation of B Cell Deficient Guinea Pig Islets of Langerhans

1971 ◽  
Vol 3 (01) ◽  
pp. 37-43 ◽  
Author(s):  
S. Howell ◽  
J. Edwards ◽  
M. Whitfield
Keyword(s):  
Guinea Pig ◽  
B Cell ◽  
Islets Of Langerhans

Electron microscopic radioautographic study of glycoprotein biosynthesis and renewal in the renal glomeruli of the rat

1978 ◽  
Vol 36 (2) ◽  
pp. 476-477
Author(s):  
A. Haddad ◽  
J-J. Lachat ◽  
R. P. Gonçalves
Keyword(s):  
Renal Cortex ◽  
Mesangial Cells ◽  
Electron Microscopic ◽  
Time Intervals ◽  
Light Microscope Level ◽  
Thin Sections ◽  
Main Site ◽  
Renal Glomeruli ◽  
Silver Grains ◽  
Electron Microscopic Radioautography

Biosynthesis, migration and renewal of glycoproteins were studied by radioautography in the renal glomeruli after administering L-3H-fucose to rats which were killed at several time intervals after injection, by perfusion of glutaraldehyde through the abdominal aorta. Small pieces of the kidney were post fixed in 0s04, dehydrated and embedded in Epon 812. Semithin and thin sections of the renal cortex were processed for light and electron microscopic radioautography, respectively. At the light microscope level (Fig. 1) it was observed that the main site of incorporation of 3H-fucose into glycoproteins was the paranuclear region of the visceral epithelial cells (podocytes). Weak paranuclear radioautographic reactions were also observed in endothelial and mesangial cells at 10 minutes after injection. At the longer time intervals these paranuclear reactions disappeared and the silver grains were mostly overlying the several components of the capillary wall. Silver grain counts showed that the peak of the silver grain density over the glomeruli occurred at 4 hours after injection; by 14 days the radioautographic reactions were almost negligible.

scholarly journals THE INFLUENCE OF DEVELOPMENT ON THE NUMBER AND APPEARANCE OF SILVER GRAINS IN ELECTRON MICROSCOPIC RADIOAUTOGRAPHY

1967 ◽  
Vol 15 (9) ◽  
pp. 501-515 ◽  
Author(s):  
BEATRIX MARKUS KOPRIWA
Keyword(s):  
Resolving Power ◽  
Silver Bromide ◽  
Grain Development ◽  
Electron Microscopic ◽  
Duration Of Action ◽  
Small Grains ◽  
Silver Grains ◽  
Electron Microscopic Radioautography ◽  
Selection Of ◽  
Duration Of Development

Under conditions similar to those in electron microscopic radioautography, the development of three different nuclear track emulsions—Ilford L4, Gevaert 307 and Kodak NTE—was investigated by varying the type of developer, duration of action and temperature. These three factors influence: (1) the number of silver grains produced from exposed silver bromide crystals and, therefore, the sensitivity of the emulsion; (2) the production of a few silver grains from silver bromide crystals, unexposed to radiation from the specimen, that is, the background fog; and (3) the size and shape of the developed silver grains, thus influencing the resolving power. The developed silver grains increase in number and in size with increasing duration of development. After complete development in most developers, the silver grains consist of highly convoluted silver filaments and are 2 or 3 times as large as the original silver bromide crystals. However, small grains may be obtained by brief development in Loveland's and p-phenylenediamine developers, in which case only development centers are revealed. Such small grain development improves resolving power, but decreases the number of developed silver grains, thus reducing sensitivity. The most satisfactory emulsion-developer combination under the conditions of the experiment appears to be Gevaert 307 emulsion developed for 2 min in D-19b. Data are also presented to facilitate the selection of the optimal emulsion-developer combination for various experimental situations.

scholarly journals L2C Guinea Pig Lymphatic Leukemia: A "B" Cell Leukemia

Blood ◽  
1972 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
E. M. Shevach ◽  
L. Ellman ◽  
J. M. Davie ◽  
I. Green
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Guinea Pig ◽  
B Cell ◽  
B Lymphocyte ◽  
Lymphoid Cells ◽  
Cell Mediated Immunity ◽  
Lymphatic Leukemia

Abstract Lymphoid cells of the immune system can be divided into two functional compartments. The thymus derived population, "T" cells, is responsible for cell mediated immunity. The bone marrow derived population, "B" cells, is responsible for antibody production. Although these two populations are functionally different, it has not yet been possible to distinguish them morphologically. Recent experimental work in the mouse has shown that the B cells bear easily detectable immunoglobulin. The T cells can be distinguished by the isoantigen, theta. The B or T cell origin of the lymphocytes of human or animal leukemia has received little attention. In the present study, we have examined the functional and morphologic properties of a guinea pig lymphatic leukemia L2C. L2C cells secrete T2 immunoglobulin and also bear this immunoglobulin on their surface. L2C cells have the recently described lymphocyte receptor for antigen-antibody-complement complexes (found on normal B lymphocytes). Finally, the L2C cell fails to be stimulated in vitro by mitogens capable of stimulating thymus-derived lymphocytes. Thus, the L2C cell appears to be of B lymphocyte origin. The availability of a large number of pure B lymphoid cells will provide a useful tool for the study of the cellular receptors of lymphoid cells and for the preparation of antisera specific for the T cell and B cell populations. The application of the techniques described in this paper to classify other lymphoid neoplasms as to their T or B cell origin may lead to both theoretic and therapeutic advances.

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