Use of saponin in the preparation of brush border from a parasitic flatworm

1981 ◽  
Vol 59 (6) ◽  
pp. 911-917 ◽  
Author(s):  
M. S. Rahman ◽  
D. F. Mettrick ◽  
R. B. Podesta
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Hymenolepis Diminuta ◽  
Parasitic Flatworm ◽  
Basal Plasma Membrane ◽  
Basal Plasma

Saponin treatment in hypotonic or hypertonic fluids, followed by vibration, was used to isolate the brush border membrane from the surface epithelial syncytium of Hymenolepis diminuta. Electron microscopy of the membrane pellets and the parasites indicated that the area of the syncytium sheered by vibration of the parasites was correlated with the areas of the syncytium in which there occurred the greatest amount of osmotically induced swelling: below and adjacent to the brush border in hypotonic incubation, and the infoldings of the basal plasma membrane of the syncytium in hypertonic incubations. Vesiculation of the microvilli occurred in incubations made hypertonic with mannitol.

Properties of a Mg2+-dependent, and Ca2+-inhibited ATPase localized in the brush border of the surface epithelial syncytium of a parasitic flatworm

1981 ◽  
Vol 59 (6) ◽  
pp. 918-923 ◽  
Author(s):  
M. Saidur Rahman ◽  
D. F. Mettrick ◽  
R. B. Podesta
Keyword(s):  
Atpase Activity ◽  
Osmotic Pressure ◽  
Brush Border ◽  
Volume Regulation ◽  
Brush Border Membrane ◽  
Ethacrynic Acid ◽  
Surface Membrane ◽  
Hymenolepis Diminuta ◽  
Parasitic Flatworm ◽  
Acid Reaction

The brush border membrane of the surface epithelial syncytium of the parasitic flatworm, Hymenolepis diminuta, was isolated by saponin treatment, and the ATPase activity was determined. The ATPase activity was insensitive to ouabain, SCN−, HCO3−, ethanol, and, although slightly inhibited by high oligomycin concentrations, was inhibited by ethacrynic acid. Reaction mixtures made increasingly hypertonic with mannitol resulted in vesicular changes in the microvilli and decreased ATPase activity. Although treatment of the brush border fraction with deoxycholate increased ATPase activity, the dependence of activity on the osmotic pressure of the reaction mixture persisted in the solubilized membrane preparations. ATPase activity was dependent upon Mg2+ and Na+ + K+ concentration. It is suggested that the ATPase in the flatworm surface membrane is involved in volume regulation in hypotonic media.

Initiation of HeLa cell adhesion to collagen is dependent upon collagen receptor upregulation, segregation to the basal plasma membrane, clustering and binding to the cytoskeleton

1992 ◽  
Vol 101 (4) ◽  
pp. 873-883
Author(s):  
M.L. Lu ◽  
R.J. McCarron ◽  
B.S. Jacobson
Keyword(s):  
Plasma Membrane ◽  
Cell Attachment ◽  
Cell Spreading ◽  
Threshold Effect ◽  
Type I ◽  
Receptor Clustering ◽  
Collagen Receptors ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Collagen Receptor

It was recently reported that HeLa cells have three Arg-Gly-Asp-dependent collagen receptors that do not appear to be in the integrin family of extracellular matrix receptors and bind to either type I or IV collagen or to type I gelatin. It was our goal to determine how these receptors function in HeLa cell-substratum adhesion. We report here that the sequence of events by which the receptors mediate adhesion to collagen or gelatin is: (1) induction of cell attachment by specific collagen receptor-substratum interactions with culture dishes covalently coated with either type I collagen or gelatin - attachment is inhibited by soluble gelatin; (2) stabilization of attachment by exocytotic upregulation of the receptors to the basal plasma membrane, which was demonstrated by analyzing, during cell adhesion, the redistribution of the collagen receptors among the apical plasma membrane exposed to the culture medium, the basal plasma membrane contacting the culture dish, and an intracellular pool of plasma membrane vesicles; (3) the initiation of cell spreading by receptor clustering and cytoskeletal association. Cell spreading is a threshold effect with regard to the surface concentration of gelatin, indicating that collagen receptor clustering is a precondition to the onset of spreading. Observations consistent with this interpretation of the threshold effect are that cells attach but spread more slowly on a substratum that retards receptor clustering, and that collagen receptors, when viewed by immunofluorescence microscopy, form a punctate pattern of fluorescence in the basal plasma membrane during cell spreading. It is also shown that more collagen receptors co-isolate with nondenaturing detergent-stable cytoskeletal preparations after the collagen receptors have been either clustered by antibodies or gelatin in solution, or by a collagen matrix. This indicates that clustering drives the receptors to bind to the cytoskeleton and is a necessary step in the transition from cell attachment to cell spreading.

Internalization and intracellular transport of folate-binding protein in rat kidney proximal tubule

1993 ◽  
Vol 264 (2) ◽  
pp. C302-C310 ◽  
Author(s):  
H. Birn ◽  
J. Selhub ◽  
E. I. Christensen
Keyword(s):  
Plasma Membrane ◽  
Proximal Tubule ◽  
Brush Border ◽  
Intracellular Transport ◽  
Brush Border Membrane ◽  
Specific Binding ◽  
Binding Protein ◽  
Rat Kidney ◽  
Folate Binding Protein

Folate-binding protein (FBP) is involved in folate reabsorption in the renal proximal tubule. Immunocytochemical studies have located FBP to the brush-border membrane, endocytic vacuoles, and dense apical tubules. We applied the same polyclonal antibody (anti-FBP) against FBP to investigate the dynamic relationship between FBP in the different compartments by microinjecting the antibody into rat kidney proximal tubules in situ. Specific binding of anti-FBP in vivo to the brush-border membrane was followed by fixation at various times. Protein A-gold labeling shows that anti-FBP is transported from endocytic invaginations into vacuoles followed by transport into dense apical tubules within 15 s. Thus FBP is rapidly internalized, and together with previous studies this study strongly suggests recycling of FBP back to the luminal plasma membrane through dense apical tubules. The results are consistent with reabsorption of folate through endocytosis of the FBP-folate complex followed by dissociation and recycling of FBP. When time is allowed there is a steady accumulation of FBP in dense apical tubules combined with an increase in surface density of the same compartment. A possible explanation involves partial inhibition of the fusion between dense apical tubules and plasma membrane because of the anti-FBP labeling of the receptor.

A transmission electron microscopical study of the tegument of Maritrema feliui (Digenea: Microphallidae)

2013 ◽  
Vol 58 (4) ◽  
Author(s):  
Zdzisław Świderski ◽  
Isabel Montoliu ◽  
Carlos Feliu ◽  
David Gibson ◽  
Jordi Miquel
Keyword(s):  
Surface Layer ◽  
Plasma Membrane ◽  
Outer Layer ◽  
Microscopical Study ◽  
The Other ◽  
Cytoplasmic Region ◽  
Transmission Electron ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Electron Microscopical

AbstractThe tegument of the microphallid digenean Maritrema feliui, examined by means of TEM, is described as a syncytial epithelium organised into two layers. The outer layer is an external anucleate, cytoplasmic region connected to a second region composed of nucleate perikarya (cytons) deeply embedded in the surrounding cortical parenchyma. The surface layer of the tegument is covered by a plasma membrane with many deep invaginations, which are apparently pinocytotic. This layer also bears numerous large, electron-dense spines of two types, which are intracellular and attached to the basal plasma membrane. Its cytoplasm is rich in free ribosomes, contains numerous mitochondria, disc-shaped granules frequently arranged in a rouleau, and several large, moderately electron-dense, membranous bodies. The subtegumentary perikarya and their nuclei, which are both flattened, are described in detail, as are their connections with the surface tegument. These perikarya appear to be the source of the disc-shaped granules and some of the other inclusions present in the surface layer. The main characteristics of the tegumental structure of M. feliui are commented upon in relation to the findings of previous publications and their suggested functions.

scholarly journals Ultrastructural Features of Gold Nanoparticles Interaction with HepG2 and HEK293 Cells in Monolayer and Spheroids

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2040 ◽  
Author(s):  
Boris Chelobanov ◽  
Julia Poletaeva ◽  
Anna Epanchintseva ◽  
Anastasiya Tupitsyna ◽  
Inna Pyshnaya ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Culture Medium ◽  
Hek293 Cells ◽  
Hydrodynamic Diameter ◽  
Multicellular Spheroids ◽  
Net Charge ◽  
Transmission Electron ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Human Embryo Kidney

Use of multicellular spheroids in studies of nanoparticles (NPs) has increased in the last decade, however details of NPs interaction with spheroids are poorly known. We synthesized AuNPs (12.0 ± 0.1 nm in diameter, transmission electron microscopy (TEM data) and covered them with bovine serum albumin (BSA) and polyethyleneimine (PEI). Values of hydrodynamic diameter were 17.4 ± 0.4; 35.9 ± 0.5 and ±125.9 ± 2.8 nm for AuNPs, AuBSA-NPs and AuPEI-NPs, and Z-potential (net charge) values were −33.6 ± 2.0; −35.7 ± 1.8 and 39.9 ± 1.3 mV, respectively. Spheroids of human hepatocarcinoma (HepG2) and human embryo kidney (HEK293) cells (Corning ® spheroid microplates CLS4515-5EA), and monolayers of these cell lines were incubated with all NPs for 15 min–4 h, and fixed in 4% paraformaldehyde solution. Samples were examined using transmission and scanning electron microscopy. HepG2 and HEK2893 spheroids showed tissue-specific features and contacted with culture medium by basal plasma membrane of the cells. HepG2 cells both in monolayer and spheroids did not uptake of the AuNPs, while AuBSA-NPs and AuPEI-NPs readily penetrated these cells. All studied NPs penetrated HEK293 cells in both monolayer and spheroids. Thus, two different cell cultures maintained a type of the interaction with NPs in monolayer and spheroid forms, which not depended on NPs Z-potential and size.

scholarly journals Insulin Stimulates GLUT4 Trafficking to the Syncytiotrophoblast Basal Plasma Membrane in the Human Placenta

2019 ◽  
Vol 104 (9) ◽  
pp. 4225-4238 ◽  
Author(s):  
Laura B James-Allan ◽  
Jaron Arbet ◽  
Stephanie B Teal ◽  
Theresa L Powell ◽  
Thomas Jansson
Keyword(s):  
Plasma Membrane ◽  
Protein Expression ◽  
Membrane Trafficking ◽  
Human Placenta ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Maternal Obesity ◽  
Normal Body Mass Index ◽  
Basal Plasma Membrane ◽  
Basal Plasma

AbstractContextPlacental transport capacity influences fetal glucose supply. The syncytiotrophoblast is the transporting epithelium in the human placenta, expressing glucose transporters (GLUTs) and insulin receptors (IRs) in its maternal-facing microvillous plasma membrane (MVM) and fetal-facing basal plasma membrane (BM).ObjectiveThe objectives of this study were to (i) determine the expression of the insulin-sensitive GLUT4 glucose transporter and IR in the syncytiotrophoblast plasma membranes across gestation in normal pregnancy and in pregnancies complicated by maternal obesity, and (ii) assess the effect of insulin on GLUT4 plasma membrane trafficking in human placental explants.Design, Setting, and ParticipantsPlacental tissue was collected across gestation from women with normal body mass index (BMI) and mothers with obesity with appropriate for gestational age and macrosomic infants. MVM and BM were isolated.Main Outcome MeasuresProtein expression of GLUT4, GLUT1, and IR were determined by western blot.ResultsGLUT4 was exclusively expressed in the BM, and IR was predominantly expressed in the MVM, with increasing expression across gestation. BM GLUT1 expression was increased and BM GLUT4 expression was decreased in women with obesity delivering macrosomic babies. In placental villous explants, incubation with insulin stimulated Akt (S473) phosphorylation (+76%, P = 0.0003, n = 13) independent of maternal BMI and increased BM GLUT4 protein expression (+77%, P = 0.0013, n = 7) in placentas from lean women but not women with obesity.ConclusionWe propose that maternal insulin stimulates placental glucose transport by promoting GLUT4 trafficking to the BM, which may enhance glucose transfer to the fetus in response to postprandial hyperinsulinemia in women with normal BMI.

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