scholarly journals THE ULTRASTRUCTURE OF THE PELLICLE COMPLEX OF EUGLENA GRACILIS

1965 ◽  
Vol 24 (2) ◽  
pp. 253-257 ◽  
Author(s):  
Joachim R. Sommer
Keyword(s):  
Cell Membrane ◽  
Euglena Gracilis ◽  
Unit Membrane ◽  
Single Row ◽  
Entire Cell

The pellicle complex of E. gracilis is composed of the cell membrane, the ridge and groove with the notch, four fibrils, and the subpellicular ER. The cell membrane is of unit membrane configuration and covers the outside of the cell, the cytostome, the gullet, and the reservoir. The notch of the pellicle complex has always a close topographic relationship to two particular fibrils, as well as the subpellicular ER. The gullet is that region between the reservoir and the cytostome which, in addition to longitudinal fibrils, is surrounded by a single row of circular fibrils. The circumference of the cytostome has twenty large pellicular ridges alternating with small pellicular ridges. Alternating tall and small pellicular ridges cover the entire cell during division.

scholarly journals LIGAND-INDUCED MOVEMENT OF LYMPHOCYTE MEMBRANE MACROMOLECULES

1973 ◽  
Vol 137 (3) ◽  
pp. 675-689 ◽  
Author(s):  
Emil R. Unanue ◽  
Morris J. Karnovsky ◽  
Howard D. Engers
Keyword(s):  
Protein Synthesis ◽  
Cell Membrane ◽  
Cell Surface ◽  
Oxidative Phosphorylation ◽  
Cross Linking ◽  
Lymphocyte Membrane ◽  
Compact Zone ◽  
Entire Cell ◽  
Freeze Etching ◽  
Spleen Lymphocytes

Spleen lymphocytes were studied for the movement and interiorization of complexes of anti-Ig-surface Ig. The movement of the complex into a small, compact zone of the cell membrane (forming a cap) was inhibited by drugs that inhibited glycolysis and oxidative phosphorylation, but not by drugs that affected protein synthesis. Dead lymphocytes did not form caps. Freeze-etching techniques revealed that inhibited lymphocytes showed formation of multiple small complexes over the entire cell surface. Inhibitors of glycolysis and of oxidative phosphorylation also inhibited the interiorization and catabolism of radioiodinated anti-Ig. We hypothesize that cross-linking of all the surface Ig triggers the membrane movements that are required to pull the lattice into one zone of the cell.

scholarly journals Ultrastructural visualization of selective peanut agglutinin binding sites in rat osteoclasts.

1988 ◽  
Vol 36 (1) ◽  
pp. 95-101 ◽  
Author(s):  
M Takagi ◽  
H Yagasaki ◽  
T Baba ◽  
H Baba
Keyword(s):  
Plasma Membrane ◽  
Cell Membrane ◽  
Cell Surface ◽  
Binding Sites ◽  
Peanut Agglutinin ◽  
Coated Pits ◽  
Cytoplasmic Surface ◽  
Coated Membranes ◽  
Entire Cell ◽  
Ruffled Border

We investigated the distribution of concanavalin A (ConA)-reactive alpha-D-mannosyl and alpha-D-glucosyl groups and peanut agglutinin (PNA)-reactive beta-D-galactose-(1----3)-N-acetyl-D-galactosamine residues on the surface of osteoclasts with pre-embedment ultrastructural lectin cytochemistry after aldehyde fixation of the metaphyses of the rat tibiae. By routine morphology, the plasma membrane of the ruffled border of the osteoclast was distinguished from the rest of the cell membrane, with the exception of the membrane of coated pits, by its characteristic thick coat at its cytoplasmic surface. Cytochemistry, using ConA in combination with horseradish peroxidase (ConA-HRP) and PNA conjugated to HRP, showed that binding of ConA was distributed over the entire cell surface of osteoclasts. In contrast, intense binding of PNA was limited to the membranes of the ruffled border and coated pits, whereas the remainder of the cell membrane stained weakly or not at all. These results demonstrate that preferential PNA binding sites of the cell surface correspond to coated membranes associated with osteoclastic endocytosis.

Ultrastructure of the Protonephridia of Syndisyrinx-Punicea (Hickman, 1956) (Rhabdocoela, Umagillidae) and Pterastericola-Pellucida Jondelius, 1989 (Rhabdocoela, Pterastericolidae)

1992 ◽  
Vol 40 (4) ◽  
pp. 385 ◽  
Author(s):  
K Rohde ◽  
NA Watson ◽  
U Jondelius
Keyword(s):  
Cell Membrane ◽  
Septate Junction ◽  
Variable Size ◽  
Single Row ◽  
Similar Morphology ◽  
Longitudinal Ribs ◽  
Surface Cell

Many flame bulbs of Syndisyrinx punicea (Rhabdocoela: Umagillidae) are formed by one perikaryon containing many mitochondria and a reticulum of membranes mainly in its periphery. Large liquid-filled lacunae were seen in the perikaryon and adjacent to it. Flame bulbs are without junctions, without external and internal leptotriches; the weir consists of some indistinct longitudinal ribs of variable size arranged in a single row, and bundles of microtubules extend along the flame bulb. Cilia are tightly packed, with microtubules oriented identically. Many flame bulbs open into one capillary with a long convoluted, partly septate junction extending to the surface cell membrane, with many microtubules running parallel with the capillary, and lateral flames. In Pterastericola pellucida (Rhabdocoela: Pterastericolidae), flame bulbs and capillaries have a similar structure, but the reticulum is more extensive, and the ribs of the weir are more distinct. The structure of the flame bulbs supports the view (based on similar morphology and hosts) that the Umagillidae and the Pterastericolidae are closely related to each other, and are typical 'turbellarian' Rhabdocoela. Many flame bulbs connected to a single perikaryon, flame bulbs with a single row of longitudinal ribs and bundles of microtubules but lacking internal leptotriches and a septate junction are synapomorphic for the Rhabdocoela (excluding the Neodermata).

Phagocytosis of concanavalin A in normal and enucleated cultures of mammalian cells

1976 ◽  
Vol 22 (3) ◽  
pp. 623-632
Author(s):  
G.E. Wise
Keyword(s):  
Cell Membrane ◽  
Concanavalin A ◽  
Mammalian Cells ◽  
Ultrastructural Level ◽  
Con A ◽  
Normal Cells ◽  
Chase Period ◽  
Entire Cell ◽  
Uniform Manner ◽  
Large Clusters

The fate of concanavalin A (Con A) bound to normal and enucleated L cells was followed at the ultrastructural level over a 20-h period. In both enucleates and normal cells the Con A is seen to be distributed in a uniform manner over the entire cell surface following a 30-min pulse with a low concentration of Con A. In the subsequent chase period the cells then aggregate the Con A and Con A sites into large clusters on the cell membrane. The cells then phagocytoze the Con A and large phagocytic vacuoles containing it are observed. Thus, enucleated cells are capable of phagocytozing Con A and its sites in the same manner as normal cells.

scholarly journals Expression of HER2 in Colorectal Cancer Does Not Correlate with Prognosis

2010 ◽  
Vol 29 (5) ◽  
pp. 207-212 ◽  
Author(s):  
Wiesław Janusz Kruszewski ◽  
Robert Rzepko ◽  
Maciej Ciesielski ◽  
Jarosław Szefel ◽  
Jacek Zieliński ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Membrane ◽  
Predictive Factor ◽  
Colorectal Adenocarcinoma ◽  
Prognostic Significance ◽  
Staining Intensity ◽  
Her2 Expression ◽  
Prognostic Information ◽  
Adenocarcinoma Cells ◽  
Entire Cell

Estimation of HER2 membranous expression is routinely used in breast and gastric cancers, as both a prognostic and a predictive factor. To date there is no evidence for similar application of HER2 expression in colorectal cancer (CRC) cells. In CRC, HER2 is sometimes overexpressed in the cell membrane and very often in the cytoplasm. This study was conducted to determine possible correlations between both membranous and cytoplasmatic expression of HER2 in CRC cells and the outcome of the disease. The prognostic significance of combined staining intensity in the cell membrane and cytoplasm in the entire CRC cell was also investigated. HER2 expression in resectable colorectal adenocarcinoma cells was evaluated by immunohistochemistry in specimens taken from 202 patients. The percentage of cancer cells with membranous or cytoplasmatic reactions and the staining intensity of the reaction in the whole cell were recorded. A membranous reaction was present in 27% of cases, and cytoplasmatic reaction in 66% of cases. The total staining intensity in the entire cell was evaluated as moderate (2+) in 32% of cases and strong (3+) staining in 15%. There was no correlation found between either membranous or cytoplasmatic HER2 expression and survival. Furthermore combined staining intensity did not provide any prognostic information. We conclude that HER2 expression in CRC does not correlate with prognosis.

Morphometric analysis of distinct microanatomy near the base of proximal tubule cells

1987 ◽  
Vol 253 (1) ◽  
pp. F126-F140 ◽  
Author(s):  
L. W. Welling ◽  
D. J. Welling ◽  
J. W. Holsapple ◽  
A. P. Evan
Keyword(s):  
Cell Membrane ◽  
Volume Fraction ◽  
Cell Model ◽  
Membrane Surface ◽  
Apical Region ◽  
Cell Height ◽  
Basolateral Cell Membrane ◽  
Entire Cell ◽  
Cell Membrane Surface ◽  
Cell Base

Models of cell shape in the rabbit S2 proximal renal tubule were derived from transmission electron micrographs and compared with scanning micrographs. Standard morphometric procedures were used to measure basolateral cell membrane surface density (SVt) relative to total epithelial volume in numerous zones of cell height. In the basal 20% region we also measured the volume fraction (F) of intercellular spaces and calculated new surface densities in reference only to the intercellular volume, SVi = SVt/F, or to the cellular volume, SVc = SVt/(1-F). Combined use of these surface densities then enabled us to calculate the diameter, length, and separation of effectively cylindrical microvilli at the cell base. Assuming that lateral cell membranes are radially oriented in the apical region but disposed on microvillus like structures of arbitrary orientation at the cell base, an improved cell model was developed that agreed with the scanning picture throughout the entire cell height. Basal microvillar elements contain approximately 60% of the total basolateral cell membrane surface area and possibly constitute a hydrostatic resistive region for absorbate flow. These features have interesting physiological implications.

scholarly journals THE CELL JUNCTION IN A LAMELLIBRANCH GILL CILIATED EPITHELIUM

1970 ◽  
Vol 47 (2) ◽  
pp. 468-487 ◽  
Author(s):  
P. Satir ◽  
N. B. Gilula
Keyword(s):  
Cell Membrane ◽  
Smooth Endoplasmic Reticulum ◽  
Freshwater Mussel ◽  
Septate Junction ◽  
Cell Junction ◽  
Junctional Complex ◽  
Regional Differentiation ◽  
Ion Permeability ◽  
Membrane Surfaces ◽  
Entire Cell

The junctional complex in the gill epithelium of the freshwater mussel (Elliptio complanatus) consists of an intermediary junction followed by a 2–3 µ long septate junction. Homologous and heterologous cell pairs are connected by this junction. After fixation with 1% OsO4 containing 1% potassium pyroantimonate, electron microscopy of the gill reveals deposits of electron-opaque precipitate, specifically and consistently localized along cellular membranes. In both junctional and nonjunctional membrane regions, the precipitate usefully outlines the convolutions without obliterating the 150 A intercellular space, which suggests the rarity or absence of either vertebrate-type gap or tight junctions along the entire cell border. The precipitate appears on the cytoplasmic side of the limiting unit membranes of frontal (F), laterofrontal (LF), intermediate (I), lateral (L), and postlateral (PL) cells. The membrane surfaces of certain vesicles of the smooth endoplasmic reticulum, of multivesicular bodies, and of mitochondrial cristae contain precipitate, as does the nucleolus. In other portions of the cell, precipitate is largely absent. The amount of over-all deposition is variable and depends on the treatment of the tissue prior to fixation. Deposition is usually enhanced by pretreatment with 40 mM NaCl as opposed to 40 mM KCl, which suggests that the precipitate is in part sodium pyroantimonate. Treatment with 0.2 mM ouabain does not enhance deposition. Regional differentiation of cell membranes with respect to their ability to precipitate pyroantimonate is found in at least three instances: (a) between the ciliary membranes and other portions of the cell membrane: the precipitate terminates abruptly at the ciliary base, (b) between the LF and I cell borders: the precipitate is asymmetric, favoring the LF side of the junction, and (c) between the septate junctional membrane and adjacent membrane: the precipitate occurs periodically throughout the septate junction region with the periodicity corresponding to the spacing of the septa. This suggests that different regions of the cell membrane may have differing ion permeability properties and, in particular, that the septa may be the regions of high ion permeability in the septate junction.

CELL MEMBRANE CONSTITUENTS CONCERNED WITH TRANSPORT MECHANISMS

1964 ◽  
Vol 42 (6) ◽  
pp. 971-988 ◽  
Author(s):  
L. S. Wolfe
Keyword(s):  
Cell Membrane ◽  
Biological Membrane ◽  
Transport Processes ◽  
Neuronal Membrane ◽  
Red Cell ◽  
Transport Mechanisms ◽  
Red Cell Membrane ◽  
Membrane Atpase ◽  
Entire Cell ◽  
And Control

The biological membrane is a multiphasic, polyionic, regionally differentiated structure, the constituents of which are closely linked to the physiological and metabolic processes of the entire cell. Knowledge of the types of molecules, their orientation, and the relative importance of them for transport processes is still very fragmentary. The information at present available on the composition of the protoplast membrane, the red cell membrane, and the neuronal membrane is brought together and discussed in terms of the possible role in transport processes. A labile phosphate attached to protein or specific phosphatides or shared between them as a lipo-phosphoprotein complex is suggested as the intermediate in the active transport of sodium. The rapid phosphorylation of these constituents by ATP through the activity of membrane ATPase and their subsequent dephosphorylation could lead to rhythmic transitions in the configuration of membrane proteins and control active cation transport.

Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

1970 ◽  
Vol 28 ◽  
pp. 104-105
Author(s):  
Hilton H. Mollenhauer ◽  
W. Evans
Keyword(s):  
Plasma Membrane ◽  
Euglena Gracilis ◽  
Complex Forms ◽  
Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

Sarcolemmal permeability changes during early myocardial anoxia

1978 ◽  
Vol 36 (2) ◽  
pp. 642-643
Author(s):  
M. Ashraf ◽  
L. Landa ◽  
L. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Cell Membrane Permeability ◽  
Enzyme Release ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sarcolemmal Permeability ◽  
Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

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