A Rapidly Sedimenting Fraction of Rat Liver Endoplasmic Reticulum

Balance-sheet experiments carried out to account for the distribution of endoplasmic reticulum fragments during subcellular fractionation of rat liver showed that a large proportion of these fragments are present in the pellets of low-speed centrifugation. Using glucose-6-phosphatase and RNA as markers we found that approximately 50% of the fragments of endoplasmic reticulum sedimented in the pellet of a 640-g centrifugation, 10% in that of a 6000-g centrifugation and 35% in the pellet of a 105000-g centrifugation. Starvation of the animals before use did not alter this distribution, nor did the use of more vigorous homogenization conditions. We have developed a procedure for removing nuclei and erythrocytes from the material sedimenting at 640g to give a fraction (rapidly sedimenting ER fraction or RS-ER) similar to the standard microsomal preparation. Centrifugation of this RS-ER fraction over 1.3 M sucrose yields subfractions of high and low RNA content analogous to the rough and smooth microsomal fractions. Electron-microscopic studies showed that, whereas the rough microsomal fraction consisted of ribosome-studded vesicles of varying size and content density, the rough RS-ER fraction contained a mixture of mitochondria and double lamellar membranes with ribosomes attached. These double lamellar membranes closely resemble the endoplasmic reticulum of intact rat liver. The double lamellar membranes are frequently observed grouped in stacks and in close association with the mitochondria. The significance of the association between endoplasmic reticulum and mitochondria of the RS-ER fraction and the relation between it and the standard microsomal preparation are discussed.

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Hepatic Ultrastructure Changes Induced by Lithocholic Acid

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060829 ◽

1967 ◽

Vol 25 ◽

pp. 162-163 ◽

Cited By ~ 1

Author(s):

F. G. Zaki

Keyword(s):

Endoplasmic Reticulum ◽

Lithocholic Acid ◽

Smooth Endoplasmic Reticulum ◽

Protein Diet ◽

Low Protein Diet ◽

Electron Microscopic ◽

Hydropic Degeneration ◽

Hepatic Cells ◽

Low Protein ◽

Microscopic Studies

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).

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Spermatogenesis in the Dragonfly with Particular Reference to the Cytoplasmic Organelles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100093808 ◽

1972 ◽

Vol 30 ◽

pp. 110-111

Author(s):

Sant S. Sekhon

Keyword(s):

Endoplasmic Reticulum ◽

Golgi Apparatus ◽

Mature Sperm ◽

Electron Microscopic ◽

Cytoplasmic Organelles ◽

Microscopic Studies ◽

Insect Sperm ◽

Large Round

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).

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The latency of rat liver microsomal protein disulphide-isomerase

Biochemical Journal ◽

10.1042/bj2280635 ◽

1985 ◽

Vol 228 (3) ◽

pp. 635-645 ◽

Cited By ~ 46

Author(s):

N Lambert ◽

R B Freedman

Keyword(s):

Endoplasmic Reticulum ◽

Rat Liver ◽

High Speed ◽

Microsomal Fraction ◽

Membrane Integrity ◽

Microsomal Protein ◽

Permeability Barrier ◽

Rat Liver Microsomes ◽

Luminal Surface ◽

Protein Disulphide Isomerase

Protein disulphide-isomerase (PDI) activity was not detectable in freshly prepared rat liver microsomes (microsomal fraction), but became detectable after treatments that damage membrane integrity, e.g. sonication, detergent treatment or freezing and thawing. Maximum activity was detectable after sonication. Identical latency was observed in microsomes prepared by gel filtration and in those prepared by high-speed centrifugation. PDI activity was latent in all particulate subcellular fractions, but not latent in the high-speed supernatant. When all fractions were sonicated to expose total PDI activity, PDI was found at highest specific activity in the microsomal fraction and co-distributed with marker enzymes of the endoplasmic reticulum. Washing of microsomes under various conditions that removed peripheral proteins and, in some cases, bound ribosomes did not remove significant quantities of PDI, nor did it affect the latency of PDI activity. Treatment of microsomes with proteinases, under conditions where the permeability barrier of the microsomal vesicles was maintained intact, did not inactivate PDI significantly or affect its latency. PDI was very readily solubilized from microsomal vesicles by low concentrations of detergents, which removed only a fraction of the total microsomal protein. In all these respects, PDI resembled nucleoside diphosphatase, a marker peripheral protein of the luminal surface of the endoplasmic reticulum, and differed from NADPH: cytochrome c reductase, a marker integral protein exposed at the cytoplasmic surface of the membrane. The data are compatible with a model in which PDI is loosely associated with the luminal surface of the endoplasmic reticulum, a location consistent with the proposed physiological role of the enzyme as catalyst of formation of native disulphide bonds in nascent and newly synthesized secretory proteins.

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Concanavalin A receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells and on cells in vivo transformed by diethylnitrosamine

Experimentelle Pathologie ◽

10.1016/s0014-4908(75)80018-4 ◽

1975 ◽

Vol 10 (3-4) ◽

pp. 143-155

Author(s):

J. Roth ◽

G. Neupert ◽

F. Bolck

Keyword(s):

Plasma Membrane ◽

Rat Liver ◽

Concanavalin A ◽

Electron Microscopic ◽

Normal Cells ◽

Rat Liver Cells ◽

Microscopic Studies ◽

Concanavalin A Receptors ◽

Comparative Electron

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A procedure for light and electron microscopic intracellular immunolocalization of collagen and fibronectin in rat liver.

Journal of Histochemistry & Cytochemistry ◽

10.1177/33.5.3886779 ◽

1985 ◽

Vol 33 (5) ◽

pp. 407-414 ◽

Cited By ~ 41

Author(s):

B Clement ◽

M Rissel ◽

S Peyrol ◽

Y Mazurier ◽

J A Grimaud ◽

...

Keyword(s):

Endothelial Cells ◽

Endoplasmic Reticulum ◽

Rat Liver ◽

Type Iii Collagen ◽

Collagen Types ◽

Electron Microscopic ◽

Experimental Conditions ◽

The Matrix ◽

Matrix Components ◽

Indirect Immunoperoxidase

Experimental conditions have been designed that permit both extracellular and intracellular immunolocalization of various collagen types and fibronectin in rat liver. The procedure involves paraformaldehyde fixation by perfusion of the organ, use of saponin as a membrane permeabilizing agent, and visualization of the matrix components by indirect immunoperoxidase. Intracellular demonstration of collagens was particularly sensitive to the composition of the fixative and the duration of fixation. Hepatocytes contained fibronectin and types I and IV collagen, whereas fat-storing and endothelial cells evidenced type III collagen in addition. All the components were specifically located in the endoplasmic reticulum and/or the Golgi apparatus.

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EFFECT OF ACTIVE ACCUMULATION OF CALCIUM AND PHOSPHATE IONS ON THE STRUCTURE OF RAT LIVER MITOCHONDRIA

The Journal of Cell Biology ◽

10.1083/jcb.23.1.21 ◽

1964 ◽

Vol 23 (1) ◽

pp. 21-38 ◽

Cited By ~ 261

Author(s):

John W. Greenawalt ◽

Carlo S. Rossi ◽

Albert L. Lehninger

Keyword(s):

Specific Gravity ◽

Rat Liver ◽

Cesium Chloride ◽

Liver Mitochondria ◽

Rat Liver Mitochondria ◽

Electron Microscopic ◽

Dense Granules ◽

Phosphate Ions ◽

Microscopic Studies

Rat liver mitochondria allowed to accumulate maximal amounts of Ca++ and HPO4= ions from the suspending medium in vitro during respiration have a considerably higher specific gravity than normal mitochondria and may be easily separated from the latter by isopycnic centrifugation in density gradients of sucrose or cesium chloride. When the mitochondria are allowed to accumulate less than maximal amounts of Ca++ and HPO4= from the medium, they have intermediate specific gravities which are roughly proportional to their content of calcium phosphate. Maximally "loaded" mitochondria are relatively homogeneous with respect to specific gravity. Correlated biochemical and electron microscopic studies show that Ca++-loaded mitochondria contain numerous dense granules, of which some 85 per cent are over 500 A in diameter. These granules are electron-opaque not only following fixation and staining with heavy metal reagents, but also following fixation with formaldehyde, demonstrating that the characteristic granules in Ca++-loaded mitochondria have intrinsic electron-opacity. The dense granules are almost always located within the inner compartment of the mitochondria and not in the space between the inner and outer membranes. They are frequently located at or near the cristae and they often show electron-transparent "cores." Such granules appear to be made up of clusters of smaller dense particles, but preliminary x-ray diffraction analysis and electron diffraction studies have revealed no evidence of crystallinity in the deposits. The electron-opaque granules decrease in number when the Ca++-loaded mitochondria are incubated with 2,4-dinitrophenol; simultaneously there is discharge of Ca++ and phosphate from the mitochondria into the medium.

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Relationship between peroxisomes and endoplasmic reticulum investigated by combined catalase and glucose-6-phosphatase cytochemistry.

Journal of Histochemistry & Cytochemistry ◽

10.1177/29.11.6274950 ◽

1981 ◽

Vol 29 (11) ◽

pp. 1263-1272 ◽

Cited By ~ 23

Author(s):

H Shio ◽

P B Lazarow

Keyword(s):

Endoplasmic Reticulum ◽

Nuclear Envelope ◽

Rat Liver ◽

Reaction Products ◽

Lead Phosphate ◽

Electron Microscopic ◽

Phosphatase Cytochemistry ◽

Electron Microscopic Cytochemistry ◽

Cellular Compartments

The theoretical advantages of electron microscopic cytochemistry were utilized to look for evidence of possible connections between peroxisomes and the endoplasmic reticulum in rat liver. Established cytochemical procedures for catalase (peroxisomes) and glucose-6-phosphatase (endoplasmic reticulum) were carried out, and evidence was sought of diffusion of reaction products between the organelles. No such diffusion was observed: lead phosphate was found in the endoplasmic reticulum and in the nuclear envelope but not in peroxisomes; oxidized diaminobenzidine (DAB) was seen only in peroxisomes. In addition, both types of cytochemistry were carried out on the same tissue. The two kinds of reaction product could be distinguished by virtue of their different electron opacities. No mixing of the two reaction products was observed. These results do not support the hypothesis that peroxisomes and endoplasmic reticulum may be connected; rather, they support the idea that the two organelles exist as separate cellular compartments.

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ELECTRON MICROSCOPY OF THE BURSA OF FABRICIUS OF THE EMBRYONIC CHICK WITH PARTICULAR REFERENCE TO THE LYMPHO-EPITHELIAL NODULES

The Journal of Cell Biology ◽

10.1083/jcb.13.1.127 ◽

1962 ◽

Vol 13 (1) ◽

pp. 127-146 ◽

Cited By ~ 67

Author(s):

G. Adolph Ackerman

Keyword(s):

Endoplasmic Reticulum ◽

Epithelial Cells ◽

Embryonic Development ◽

Golgi Complex ◽

Bursa Of Fabricius ◽

Cortical Region ◽

Electron Microscopic ◽

Submicroscopic Structure ◽

Microscopic Studies ◽

Pass Through

Electron microscopic studies of the bursa of Fabricius during the 15th and 16th day of embryonic development in the chick have shown the following findings in the submicroscopic structure of the cellular elements of the lympho-epithelial follicles. In the medulla, basal endodermal epithelial cells undergo mitosis and differentiation into lymphoblasts. During this transformation, there is a reduction in the amount of rough endoplasmic reticulum, an increase in the number or ribosomes, and frequently an enlargement of the Golgi complex. As lymphoblasts differentiate into medium lymphocytes there is a loss of endoplasmic reticulum, a reduction in the number of ribosomes and in the size of the Golgi complex, as well as a decrease in the number and size of mitochondria and in the size of the cell and nucleus. Cytoplasmic processes of reticular-epithelial cells extend between proliferating lymphocytic cells. Desmosomes connect stellate reticular-epithelial and basal epithelial cells but are not present in lymphocytic cells. Nuclear blebbing and vesiculation are frequently observed in the various cell forms of the developing lympho-epithelial nodules. Although lymphocytes and lymphocytopoietic activities in the cortex are sparse during this stage of embryonic development of the bursa, transitional forms between mesenchymal cells and lymphoblasts have been encountered. In addition, lymphoblasts and/or undifferentiated epithelial cells occasionally may pass through the basement membrane from the medulla into the cortical region of the developing nodule. That lymphocytes in the bursa of Fabricius originate from both endodermal and mesodermal derivatives during embryonic development appears to be consistent with both light and electron microscopic observations.

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Immuno-electron-microscopic studies on the subcellular distribution of rat liver epoxide hydrolase and the effect of phenobarbitone and 2-acetamidofluorene treatment

Biochemical Journal ◽

10.1042/bj2020677 ◽

1982 ◽

Vol 202 (3) ◽

pp. 677-686 ◽

Cited By ~ 5

Author(s):

F Waechter ◽

P Bentley ◽

M Germann ◽

F Oesch ◽

W Stäubli

Keyword(s):

Electron Microscopy ◽

Rat Liver ◽

Subcellular Distribution ◽

Epoxide Hydrolase ◽

Specific Binding ◽

Subcellular Fractions ◽

Electron Microscopic ◽

Immuno Electron Microscopy ◽

Microscopic Studies ◽

The Individual

The distribution of rat liver epoxide hydrolase in various subcellular fractions was investigated by immuno-electron-microscopy. Ferritin-linked monospecific anti-(epoxide hydrolase) immunoglobulins bound specifically to the cytoplasmic surfaces of total microsomal preparations and smooth and rough microsomal fractions as well as the nuclear envelope. Specific binding was not observed when the ferritin conjugates were incubated with peroxisomes, lysosomes and mitochondria. The average specific ferritin load of the individual subcellular fractions correlated well with the measured epoxide hydrolase activities. This correlation was observed with fractions prepared from control, phenobarbitone-treated and 2-acetamidofluorene-treated rats.

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