Plasma Membrane Biogenesis

1974 ◽  
Vol 32 ◽  
pp. 312-313
Author(s):  
Russell J. Barrnett
Keyword(s):  
Plasma Membrane ◽  
Trigeminal Nerve ◽  
Salt Gland ◽  
Ultrastructural Localization ◽  
Secretory Cells ◽  
Membrane Biogenesis ◽  
Cell Plasma ◽  
Microsome Fraction ◽  
Myelin Fraction

This report presents two examples of plasma membrane biogenesis in which the synthesis and assembly of components, phospholipid and enzyme proteins, were studies by a combination of biochemistry, cytochemistry and electron microscopy. These were: the proliferation of Schwann cell plasma membrane during the process of myelination of the trigeminal nerve in neonatal rats and amplification of the plasma membrane at the lateral and basal borders of secretory cells of the ducklings' salt gland as a result of salt stress.In the study concerning myelination a method for the ultrastructural localization of acyltransferase activities (the first two steps in phospholipid synthesis) was applied to the developing rat trigeminal nerve. Determination of acyltransferase levels in the nerve indicated that a peak of activity occurs at the 8th day after birth with gradual declines of activity up to 15 days. This peak coincided with the peak of a-glycerophosphate incorporation into phospholipids in the microsome fraction of the nerve: wheras, no incorporation was noted in the myelin fraction.

scholarly journals ULTRASTRUCTURAL LOCALIZATION OF PHOSPHOLIPID SYNTHESIS IN THE RAT TRIGEMINAL NERVE DURING MYELINATION

1973 ◽  
Vol 57 (3) ◽  
pp. 613-629 ◽  
Author(s):  
Francine Benes ◽  
Joan A. Higgins ◽  
Russell J. Barrnett
Keyword(s):  
Plasma Membrane ◽  
Schwann Cell ◽  
Ganglion Cell ◽  
Trigeminal Nerve ◽  
Ultrastructural Localization ◽  
Phospholipid Metabolism ◽  
Myelin Formation ◽  
Cholesterol Levels ◽  
Myelin Fraction

A method for the ultrastructural localization of acyltransferase enzymes involved in phospholipid metabolism has been applied to the developing rat trigeminal nerve. Determination of acyltransferase levels in the nerve indicated that a peak of activity occurs at the 8th day after birth with gradual declines of activity up to 15 days. Morphological surveys and determinations of cholesterol levels suggested that heavy myelin formation occurs in the nerve during this latter period. Fixed nerves incubated in a medium for localization of acyltransferases indicated deposition of reaction product associated with Golgi cisternae, intracellular smooth vesicles, and the plasma membrane of the Schwann cell in the incipient stages of myelin formation. Golgi-derived vesicles appeared to move toward the Schwann cell surface and fuse with the plasma membrane. Activity continued to be detectable in the plasma membrane of the internal mesaxon as long as cytoplasm was evident and mature myelin membrane was not yet formed. Cells in which myelin formation appeared advanced showed little or no enzyme marker. Consistent with cytochemical observations were biochemical determinations of acyltransferases which showed high levels of the enzymes in microsomes, while no activity could be detected in the myelin fraction. Acyltransferase reaction product was also observed in the Golgi apparatus of ganglion cell bodies, axoplasmic smooth vesicles, and the axolemma. Localization of acyltransferase enzymes in Schwann cells, ganglion cell bodies, and axons during development of the nerve is discussed in relation to membrane biogenesis in the nervous system.

Biogenesis of Plasma Membranes in Salt Glands of Salt-Stressed Domestic Ducklings: Localization of Acyltransferase Activity

1972 ◽  
Vol 11 (3) ◽  
pp. 855-873
Author(s):  
A. M. LEVINE ◽  
JOAN A. HIGGINS ◽  
R. J. BARRNETT
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Salt Gland ◽  
Secretory Cells ◽  
Salt Glands ◽  
Acyltransferase Activity ◽  
Structural Localization ◽  
Differentiated Cells ◽  
Golgi Membranes

In response to salt water stress there is a marked increase in the plasma membranes of the epithelial secretory cells of the salt glands of domestic ducklings. In the present study, the fine-structural localization of the acyltransferases involved in synthesis of phospholipids has been investigated in this tissue during this increased biogenesis of plasma membranes. The specific activity of the acyltransferases of the salt gland rose in response to salt stress, and this preceded the rapid increase in weight and cellular differentiation. After the weight increase of the gland became established, the specific activity of the acyltransferases declined, but the total activity remained constant. Salt gland tissue fixed in a mixture of glutaraldehyde and formaldehyde retained 35% of the acyltransferase activity of unfixed tissue. Cytochemical studies of the localization of acyltransferase activity in fixed and unfixed salt gland showed reaction product associated only with the lamellar membranes of the Golgi complex. This localization occurred in partially differentiated cells from salt-stressed glands to the greatest extent; and to only a small extent in cells of control tissue from unstressed salt glands. Omission of substrates resulted in absence of reaction product in association with the Golgi membranes. In addition, vesicles having limiting membranes morphologically similar to the plasma membrane occurred between the Golgi region and the plasma membrane in the partially differentiated cells. The phospholipid component of the plasma membrane appears therefore to be synthesized in association with the Golgi membranes and the membrane packaged at this site from which it moves in the form of vesicles to fuse with the pre-existing plasma membrane.

scholarly journals Fusion pore or porosome: structure and dynamics

2003 ◽  
Vol 176 (2) ◽  
pp. 169-174 ◽  
Author(s):  
BP Jena
Keyword(s):  
Plasma Membrane ◽  
Neuroendocrine Cells ◽  
Fusion Pore ◽  
Secretory Cells ◽  
Force Microscopy ◽  
Membrane Pores ◽  
Atomic Force ◽  
Cell Plasma ◽  
Electrophysiological Measurements ◽  
Membrane Bound

Electrophysiological measurements on live secretory cells almost a decade ago suggested the presence of fusion pores at the cell plasma membrane. Membrane-bound secretory vesicles were hypothesized to dock and fuse at these sites, to release their contents. Our studies using atomic force microscopy on live exocrine and neuroendocrine cells demonstrate the presence of such plasma membrane pores, revealing their morphology and dynamics at near nm resolution and in real time.

Ultrastructural localization of alkaline phosphatase in lactating rat mammary gland

1988 ◽  
Vol 46 ◽  
pp. 390-391
Author(s):  
Harold M. Farrell ◽  
Beverly E. Maleeff ◽  
Cecilia T. Leung
Keyword(s):  
Alkaline Phosphatase ◽  
Plasma Membrane ◽  
Calcium Phosphate ◽  
Milk Fat ◽  
Mammalian Cells ◽  
Plasma Membranes ◽  
Ultrastructural Localization ◽  
Apical Plasma Membrane ◽  
Secretory Cells ◽  
Colloidal Calcium Phosphate

Alkaline phosphatase is found in almost all nucleated mammalian cells as well as in many microorganisms. In animal tissues, it is often found associated with plasma membranes and also has been indirectly implicated in the accumulation of calcium-phosphate in calcifying tissue, osteoblasts and odontoblasts. In the secretion of milk, vesicles accumulate casein and colloidal calcium-phosphate, while in a separate pathway milk fat is secreted and bounded by the apical plasma membrane. Alkaline phosphatase is found in milk, and all milks contain both colloidal calcium-phosphate and fat globule membranes which are derived in part from the plasma membrane. Previous studies had suggested that mammary alkaline phosphatase is limited to nonsecretory myoepithelial cells, but recent work has indicated that intracellular alkaline phosphatase is cryptic. We therefore decided to investigate the cytochemical distribution of alkaline phosphatase in mammary secretory cells, and to determine if it could participate in calcium-phosphate accumulation in milk.

scholarly journals Basolateral plasma membrane localization of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland

1977 ◽  
Vol 75 (1) ◽  
pp. 74-94 ◽  
Author(s):  
SA Ernst ◽  
JW Mills
Keyword(s):  
Plasma Membrane ◽  
Binding Sites ◽  
Salt Gland ◽  
Physiological Data ◽  
Secretory Cells ◽  
Ouabain Binding ◽  
Salt Glands ◽  
Cytochemical Localization ◽  
Secretory Epithelium ◽  
Basolateral Plasma Membrane

The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 μM ouabain (containing 5 μCi/ml [(3)H]ouabain) for 90 min. Washing with label-free Ringer's solution for 90 min extracted only 10% of the inhibitor, an amount which corresponded to ouabain present in the tissue spaces labeled by [(14)C]insulin. Increasing the KCl concentration of the incubation medium reduced the rate of ouabain binding but not the maximal amount bound. In contrast to the low level of ouabain binding to salt glands of ducks maintained on a freshwater regimen, exposure to a salt water diet led to a more than threefold increase in binding within 9-11 days. This increase paralleled the similar increment in Na+-K+-ATPase activity described previously. [(3)H]ouabain binding sites were localized autoradiographically to the folded basolateral plasma membrane of the principal secretory cells. The luminal surfaces of these cells were unlabeled. Mitotically active peripheral cells were also unlabeled. The cell-specific pattern of [(3)H]ouabain binding to principal secretory cells and the membrane-specific localization of binding sites to the nonluminal surfaces of these cells were identical to the distribution of Na+-K+-ATPase as reflected by the cytochemical localization of ouabain-sensitive and K+-dependent nitrophenyl phosphatase activity. The relationship between the nonluminal localization of Na+-K+-ATPase and the possible role of the enzyme n NaCl secretion is considered in the light of physiological data on electrolyte transport in salt glands and other secretory epithelia.

TRANSPORT ADENOSINE TRIPHOSPHATASE CYTOCHEMISTRY II. CYTOCHEMICAL LOCALIZATION OF OUABAIN-SENSITIVE, POTASSIUM-DEPENDENT PHOSPHATASE ACTIVITY IN THE SECRETORY EPITHELIUM OF THE AVIAN SALT GLAND

1972 ◽  
Vol 20 (1) ◽  
pp. 23-38 ◽  
Author(s):  
STEPHEN A. ERNST
Keyword(s):  
Phosphatase Activity ◽  
Adenosine Triphosphatase ◽  
Plasma Membranes ◽  
Salt Gland ◽  
Ultrastructural Localization ◽  
Defined Medium ◽  
Secretory Cells ◽  
Cytochemical Localization ◽  
Fixed Tissue ◽  
Nitrophenyl Phosphate

A cytochemical procedure is described for the ultrastructural localization of K-dependent, ouabain-sensitive nitrophenyl phosphatase activity in avian salt gland. Cryostat sections (50 µ) of paraformaldehyde-fixed tissue were incubated in a kinetically defined medium containing: 5 mM p-nitrophenyl phosphate, 10 mM MgCl2, 10 mM KCl, 100 mM Tris-HCl buffer (pH 8.5 or 9.0) and 20 mM SrCl2 to precipitate hydrolyzed phosphate. After incubation at room temperature, the sections were treated with Pb(NO3)2 to convert SrPi to PbPi precipitates for visualization in the electron microscope. Reaction product was localized on the cytoplasmic side of the secretory cell lateral and basal plasma membranes. Little, if any, reaction product was associated with the apical surfaces of the secretory cells or with endothelial surfaces of capillaries. Appropriate control experiments indicated that deposition of reaction product was dependent on Mg and K and was sensitive to ouabain. Furthermore, nonenzymatic hydrolysis of nitrophenyl phosphate did not occur in the medium, and deposition of artifactually produced precipitates did not resemble deposition of enzymatically produced precipitates. The relationship of this localization to transport adenosine triphosphatase cytochemistry is discussed, and the physiologic implications of the localization for tracing the route of active Na transport in the salt gland are considered.

Morphology of isolated crustacean larval salt glands

1985 ◽  
Vol 248 (6) ◽  
pp. R709-R716
Author(s):  
R. J. Lowy ◽  
F. P. Conte
Keyword(s):  
Plasma Membrane ◽  
Salt Gland ◽  
Artemia Salina ◽  
Apical Plasma Membrane ◽  
Secretory Cells ◽  
Cell Contact ◽  
Salt Glands ◽  
Transmission Electron

Larval salt glands isolated from the naupliar brine shrimp (Artemia salina) were examined using light microscopy and scanning and transmission electron microscopy. These methods demonstrated that most cellular and subcellular features of the in vitro organ compared favorably with those seen in vivo. This salt gland measures 130 micron in diameter and is comprised of 50-70 secretory cells, which are of a single epithelial cell type. Characteristic ultrastructural features that are well preserved include apical to basal cell polarity, apical plasma membrane projections, and the extent of the basolateral tubular labyrinth and its association with numerous mitochondria. Some features that have been altered are a decrease in cell-cell contact, separation of septate junctions, and expansion of tubular labyrinth lumens and mitochondrial cristae. Use of this preparation has allowed examination of the salt gland cell's hemocoelic surface for the first time and provided information about the ultrastructure of the tufts formed by the apical plasma membrane.

Multimodal Atomic Force Imaging of Open Hemichannelinduced Modulation of Cell Volume and Viscoelastic Properties

1999 ◽  
Vol 5 (S2) ◽  
pp. 998-999
Author(s):  
Seung K. Rhee ◽  
Arjan P. Quist ◽  
Hai Lin ◽  
Nils Almqvist ◽  
Ratneshx Lai
Keyword(s):  
Plasma Membrane ◽  
Cell Volume ◽  
Lucifer Yellow ◽  
Single Cells ◽  
Dye Uptake ◽  
Aortic Endothelial Cells ◽  
Atomic Force ◽  
Cell Plasma ◽  
Uptake Assay ◽  
Gap Junctional

Hemichannels from two single cells can join upon contact between these cells to form gap junctions - an intercellular pathway for the direct exchange of ions and small metabolites. Using techniques of fluorescent dye-uptake assay, laser confocal fluorescence imaging and atomic force microscopy (AFM), we have examined the role of hemichannels, present in the non-junctional regions of single cell plasma membrane, in the modulation of cell volume.Antibodies against a gap junctional protein connexin43, were immunolocalized to nonjunctional plasma membrane regions of single BICR-MlRk k (breast tumor epithelial) cells, KOM-1 (bovine aortic endothelial) cells, and GM04260 (AD-free human) fibroblast cells. In the absence of extracellular calcium, cytoplasmic uptake of Lucifer yellow (LY) but not of dextran-conjugated LY was observed in single cells. Dye uptake was prevented by gap junctional inhibitors, ẞ-glycyrrhetinic acid (ẞGCA) and oleamide.

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