PANCREATIC MICROSOMES

G. E. Palade; P. Siekevitz

doi:10.1083/jcb.2.6.671

PANCREATIC MICROSOMES

The Journal of Cell Biology ◽

10.1083/jcb.2.6.671 ◽

1956 ◽

Vol 2 (6) ◽

pp. 671-690 ◽

Cited By ~ 228

Author(s):

G. E. Palade ◽

P. Siekevitz

Keyword(s):

Endoplasmic Reticulum ◽

Islet Cells ◽

Reductase Activity ◽

Liver Microsomes ◽

Basal Region ◽

Cytoplasmic Matrix ◽

Exocrine Cells ◽

Dense Granules ◽

Microsome Fraction ◽

Pancreatic Exocrine

The pancreatic exocrine cell of the guinea pig has a voluminous endoplasmic reticulum distinguished by extensive association with small, dense particles, and by its orderly disposition in the basal region of the cell. In addition to the small, (∼15 mµ), dense particles attached to the limiting membrane of the endoplasmic reticulum, numerous particles of similar appearance are found freely scattered in the cytoplasmic matrix. The various cell structures of pancreatic exocrine cells can be satisfactorily identified in pancreatic homogenates. The microsome fraction consists primarily of spherical vesicles (80 to 300 mµ), limited by a thin membrane (7 mµ) which bears small (∼15 mµ) dense particles attached on its outer surface. The content of the microsomal vesicles is usually of high density. Pancreatic microsomes derive by extensive fragmentation mainly from the rough surfaced parts of the endoplasmic reticula of exocrine cells. A few damaged mitochondria and certain dense granules (∼150 mµ) originating probably from islet cells, contaminate the microsome fraction. Pancreatic microsomes contain RNA, protein, and a relatively small amount of phospholipide and hemochromogen. They do not have DPNH-cytochrome c reductase activity. In six experiments the RNA/protein N ratios were found grouped around two different means, namely 0.6 and 1.3. Pancreatic microsomes are more labile than liver microsomes but react in a similar way to RN-ase-(loss of the particulate component and RNA), and deoxycholate treatment (loss of the membranous component and of phospholipide, hemochromogen, and most of the protein). Postmicrosomal fractions consisting primarly of small (∼15 mµ), dense particles of ribonucleoprotein (RNA/protein N ratio = 1 to 2) were obtained by further centrifugation of the microsomal supernatant. The small nucleoprotein particles of these fractions are frequently found associated in chains or clusters.

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FINE STRUCTURE OF DIFFERENTIATING MOUSE PANCREATIC EXOCRINE CELLS IN TRANSFILTER CULTURE

The Journal of Cell Biology ◽

10.1083/jcb.20.3.399 ◽

1964 ◽

Vol 20 (3) ◽

pp. 399-413 ◽

Cited By ~ 63

Author(s):

Frances Kallman ◽

Clifford Grobstein

Keyword(s):

Endoplasmic Reticulum ◽

Epithelial Surface ◽

Embryonic Mouse ◽

Exocrine Cells ◽

Differentiated Cells ◽

Pancreatic Epithelium ◽

Pancreatic Exocrine ◽

Transfilter Culture ◽

Specific Synthesis ◽

Made In

Fine structural observations have been made in the 11-day embryonic mouse of exocrine cells in pancreatic epithelium developing in tissue culture transfilter from salivary gland mesenchyme of the 13-day embryonic mouse. After 2 days in culture, the exocrine cells show increased cytoplasmic density, abundant ribosomes in aggregate or "rosette" form, and expanded profiles of rough-surfaced endoplasmic reticulum. After 3 and 4 days in culture, the cells exhibit continued expansion of the profiles of endoplasmic reticulum, increased amounts of Golgi membranes, and large areas of light density (prozymogen granules). After 5 days in culture, dense zymogen granules are present in the most highly differentiated cells. In addition, at the filter-epithelial surface, at 2 days, small fibers can be discerned which, after 4 days in culture, show obvious periodicity and are thought to be collagen. The significance of these changes, in relation to the mesenchymal effect, to the onset of specific synthesis and to the stabilization of differentiation is discussed.

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Seasonal Changes in the Fine Structure of the Basal Granular Cells of the Bat Thyroid

Journal of Cell Science ◽

10.1242/jcs.2.3.401 ◽

1967 ◽

Vol 2 (3) ◽

pp. 401-410

Author(s):

E. A. NUNEZ ◽

R. P. GOULD ◽

D. W. HAMILTON ◽

J. S. HAYWARD ◽

S. J. HOLT

Keyword(s):

Fine Structure ◽

Seasonal Changes ◽

Follicular Epithelium ◽

Thyroid Cell ◽

Basal Region ◽

Basal Cells ◽

Uniform Size ◽

Thyroid Cells ◽

Cytoplasmic Matrix ◽

Dense Granules

The fine structure of the thyroid gland of non-hibernating, hibernating, and intermittently aroused hibernating bats was examined. It was found that in addition to the ordinary follicular cell, another widespread thyroid cell type is present in all bats examined. This cell is situated in the basal region of the thyroid follicle and is characterized by a cytoplasm full of secretory-like granules. In the basal cells of bats captured in April and June the granules consist of an extremely dense core and are of a uniform size averaging from 0.1-0.5 µ in diameter. In bats caught in August the solid dense granules vary greatly in size and large granules of diameters from 2 to 5 µ are common. These large granules are often found concentrated in groups in the most basal region of the follicular epithelium. Hibernating bats are characterized by partly or totally degranulated basal thyroid cells. The cytoplasmic granules in the partly degranulated cell vary greatly in appearance, ranging from solid dense granules to empty vesicles. In totally degranulated basal cells, empty vesicles fill the cytoplasmic matrix. The granular endoplasmic reticulum of the basal thyroid cell also shows seasonal changes, while the Golgi complex remains a well-developed organelle throughout the year. These observations suggest that the thyroid basal granular cell is involved in secretory activities; its possible functional role is discussed.

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ACTIVE TRANSPORT BY THE CECROPIA MIDGUT

The Journal of Cell Biology ◽

10.1083/jcb.31.1.107 ◽

1966 ◽

Vol 31 (1) ◽

pp. 107-134 ◽

Cited By ~ 184

Author(s):

Everett Anderson ◽

William R. Harvey

Keyword(s):

Endoplasmic Reticulum ◽

Plasma Membrane ◽

Goblet Cell ◽

Plasma Membranes ◽

Goblet Cells ◽

Potassium Transport ◽

Columnar Cell ◽

Morphological Data ◽

Basal Region ◽

Cytoplasmic Matrix

A morphological basis for transcellular potassium transport in the midgut of the mature fifth instar larvae of Hyalophora cecropia has been established through studies with the light and electron microscopes. The single-layered epithelium consists of two distinct cell types, the columnar cell and the goblet cell. No regenerative cells are present. Both columnar and goblet cells rest on a well developed basement lamina. The basal portion of the columnar cell is incompletely divided into compartments by deep infoldings of the plasma membrane, whereas the apical end consists of numerous cytoplasmic projections, each of which is covered with a fine fuzzy or filamentous material. The cytoplasm of this cell contains large amounts of rough endoplasmic reticulum, microtubules, and mitochondria. In the basal region of the cell the mitochondria are oriented parallel to the long axes of the folded plasma-lemma, but in the intermediate and apical portions they are randomly scattered within the cytoplasmic matrix. Compared to the columnar cell, the goblet cell has relatively little endoplasmic reticulum. On the other hand, the plications of the plasma membrane of the goblet cell greatly exceed those of the columnar cell. One can distinguish at least four characteristic types of folding: (a) basal podocytelike extensions, (b) lateral evaginations, (c) apical microvilli, and (d) specialized cytoplasmic projections which line the goblet chamber. Apically, the projections are large and branch to form villus-like units, whereas in the major portion of the cavity each projection appears to contain an elongate mitochondrion. Junctional complexes of similar kind and position appear between neighboring columnar cells and between adjacent columnar and goblet cells as follows: a zonula adherens is found near the luminal surface and is followed by one or more zonulae occludentes. The morphological data obtained in this study and the physiological information on ion transport through the midgut epithelium have encouraged us to suggest that the goblet cell may be the principal unit of active potassium transport from the hemolymph to the lumen of the midgut. We have postulated that ion accumulation by mitochondria in close association with plicated plasma membranes may play a role in the active movement of potassium across the midgut.

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ELECTRON MICROSCOPE EXAMINATION OF SUBCELLULAR FRACTIONS

The Journal of Cell Biology ◽

10.1083/jcb.51.1.52 ◽

1971 ◽

Vol 51 (1) ◽

pp. 52-71 ◽

Cited By ~ 62

Author(s):

Maurice Wibo ◽

Alain Amar-Costesec ◽

Jacques Berthet ◽

Henri Beaufay

Keyword(s):

Endoplasmic Reticulum ◽

Electron Microscope ◽

Membrane Protein ◽

Distribution Pattern ◽

Biochemical Analysis ◽

Liver Microsomes ◽

Rat Liver Microsomes ◽

Microscope Examination ◽

Membrane Area ◽

Microsome Fraction

Rat liver microsomes and microsomal subfractions isolated by density equilibration were submitted to a quantitative morphological and biochemical analysis. The total area of the endoplasmic reticulum was estimated at 7.3 m2 per g of liver. The microsome fraction contained 2.8 mg of phospholipids and 6.7 mg of proteins per m2 of membrane area. After correction for ribosomal and intracisternal proteins, the latter value was lowered to 4.7 mg of membrane protein per m2. More than half of the microsomal vesicles carried ribosomes. After density equilibration of the microsomes, the distribution pattern of ribosomes followed closely that of RNA. The ribosome load of the microsomal vesicles increased steadily along the density gradient, indicating the existence of a continuous spectrum of microsomal entities ranging from entirely ribosome-free vesicles to vesicles heavily coated with ribosomes.

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Osmotic Separation of Pancreatic Exocrine Cells from Crude Islet Cell Preparations

Cell Transplantation ◽

10.1177/096368979600500107 ◽

1996 ◽

Vol 5 (1) ◽

pp. 31-39 ◽

Cited By ~ 2

Author(s):

Chi Liu ◽

Locksley E. Mcgann ◽

Dayong Gao ◽

Brian W. Haag ◽

John K. Critser

Keyword(s):

Mitochondrial Function ◽

Islet Cell ◽

Treatment Time ◽

Islet Cells ◽

Membrane Integrity ◽

Cell Lysis ◽

Exocrine Cells ◽

Hypotonic Treatment ◽

Pancreatic Exocrine ◽

Exocrine Cell

A novel approach is introduced here to selectively lyse exocrine cells in an islet preparation by hypoosmotic treatment. Time to hypotonic cell lysis required for the islet cells was much longer than that for the exocrine cells, which permits a possibility of selectively killing the exocrine cells by hypotonic treatment. The first set of experiments was designed to select an appropriate osmolality for the hypotonic treatment. Kinetic changes in cell volume in response to extracellular anisosmolalities (30 to 90 mOsm/kg) were recorded using an electronic particle counter. The results indicated that, when exposed to a 30 mOsm/kg solution, islet cells swelled slowly to reach volumetric equilibrium in approximately 3 min. There was no significant hypotonic cell lysis observed even at the end of 4 min (n = 4). In contrast, pancreatic exocrine cells, when exposed to the same solution, expanded rapidly to the lytic volume and burst within 30 s. Significant exocrine cell lysis was invariably achieved within 30 s when cells were exposed to the osmolalities below 60 mOsm/kg. For osmolalities between 70 to 80 mOsm/kg, exocrine cell lysis was highly variable. When cells were exposed to 80 to 90 mOsm/kg, no significant cell lysis was observed. Thus, an osmolality of 50 mOsm/kg is recommended for hypotonic treatment, as it maximizes the lysis of exocrine cells without unnecessarily stressing (osmotically) the islet cells. The second set of experiments (time-course experiments, 20 to 120 s) was designed to determine the length of exposure time for which the exocrine cells were irreversibly damaged but the islet cells had only swollen to such a degree that cell function is restored upon returning to an isotonic condition. Viability of the hypotonic treated cells was evaluated at two different levels: membrane integrity, measured by combined fluorescent dye staining with propidium iodide (PI) and carboxyfluorescein diacetate (CFDA), and mitochondrial function, measured by colorimetric MTT assay. The results showed that hypotonic treatment in a 50 mOsm/kg solution for 30 s resulted in over 85% loss of the membrane integrity for the exocrine cells. About 90% of these membrane lysed cells lost mitochondrial function (n = 3). By contrast, under the same treatment, less than 15% of the islet cells lost membrane integrity and mitochondrial function (n = 3). In conclusion, hypotonic treatment with a 50 mOsm/kg solution for 20 to 30 s at room temperature is sufficient to lyse the majority of the contaminating exocrine cells in an islet cell preparation, while maintaining function in the islet cells.

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ELECTRON MICROSCOPY OF HELA CELLS AFTER THE INGESTION OF COLLOIDAL GOLD

The Journal of Cell Biology ◽

10.1083/jcb.3.5.749 ◽

1957 ◽

Vol 3 (5) ◽

pp. 749-756 ◽

Cited By ~ 41

Author(s):

Carl G. Harford ◽

Alice Hamlin ◽

Esther Parker

Keyword(s):

Electron Microscopy ◽

Endoplasmic Reticulum ◽

Cell Membrane ◽

Golgi Complex ◽

Hela Cells ◽

Colloidal Gold ◽

Tissue Cultures ◽

Cytoplasmic Matrix ◽

Gold Particles ◽

Dense Granules

Tissue cultures of HeLa cells were grown in media containing colloidal gold, and after various intervals, the cells were fixed, embedded, and sectioned for electron microscopy. Uncoated grids with small holes were used in many of the experiments. Intracellular particles of gold were identified in areas surrounded by single membranes, in moderately dense granules, in globoid bodies, and in the cytoplasmic matrix. Gold particles were not found in typical mitochondria, Golgi complex, ergastoplasm (granular forms of endoplasmic reticulum), or nuclei. The phenomenon of pinocytosis was considered to be the most likely means by which the gold particles were ingested, and the locations of gold particles appeared to have significance concerning theories that membranous organelles of the cytoplasm may be derived from the cell membrane.

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Biosynthesis of microsomal nicotinamide–adenine dinucleotide phosphate–cytochrome c reductase by membrane-bound and free polysomes from rat liver

Biochemical Journal ◽

10.1042/bj1120139 ◽

1969 ◽

Vol 112 (2) ◽

pp. 139-147 ◽

Cited By ~ 90

Author(s):

G. Ragnotti ◽

G. R. Lawford ◽

P. N. Campbell

Keyword(s):

Endoplasmic Reticulum ◽

Rat Liver ◽

Specific Activity ◽

Reductase Activity ◽

Gel Filtration ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

High Specific Activity ◽

Rat Liver Cells ◽

Microsome Fraction ◽

Membrane Bound

1. NADPH–ferricytochrome c oxidoreductase (EC 1.6.2.3) was purified from the endoplasmic reticulum of rat liver cells. The methods, which involved digestion of membrane with Steapsin, a crude pancreatic extract containing diastase and trypsin, gel filtration and preparative electrophoresis on polyacrylamide, provided an enzyme with a high specific activity in good yield. 2. The incorporation of 14C-labelled amino acids into the purified reductase by the incubation of various subcellular fractions was studied. The microsome fraction, bound polysomes, free polysomes and detergent-treated polysomes effected the synthesis of the enzyme. 3. The reductase that had been synthesized by the polysomes was tightly bound to preparations of smooth-surfaced endoplasmic reticulum that were added to the incubation medium. 4. Reductase activity could be detected on both free and detergent-treated polysomes. Evidence is presented to show that this activity was due, at least in part, to the presence on the ribosomes of nascent enzyme. The association of enzyme with detergent-treated polysomes did not appear to be due to contamination of the ribosomes with either membrane or cell sap but it is possible for such ribosomes to adsorb some enzyme. 5. The amount of reductase activity associated with the detergent-treated polysomes was increased when the rats from which the polysomes were derived had been previously injected with phenobarbitone. 6. The results are discussed with respect to their relevance for the question of the existence of two functionally different groups of polysomes in the liver and for current ideas on the biogenesis of membranes.

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