scholarly journals Comparative ultrastructure of cells and cuticle in the anterior chamber and papillate region of Porcellio scaber (Crustacea, Isopoda) hindgut

ZooKeys ◽  
2018 ◽  
Vol 801 ◽  
pp. 427-458 ◽  
Author(s):  
Urban Bogataj ◽  
Monika Praznik ◽  
Polona Mrak ◽  
Jasna Štrus ◽  
Magda Tušek-Žnidarič ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Anterior Chamber ◽  
Plasma Membranes ◽  
Cell Junctions ◽  
Apical Plasma Membrane ◽  
Septate Junctions ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Cuticle Ultrastructure

Isopod hindgut consists of two anatomical and functional parts, the anterior chamber, and the papillate region. This study provides a detailed ultrastructural comparison of epithelial cells in the anterior chamber and the papillate region with focus on cuticle ultrastructure, apical and basal plasma membrane labyrinths, and cell junctions. Na+/K+-ATPase activity in the hindgut epithelial cells was demonstrated by cytochemical localisation. The main difference in cuticle ultrastructure is in the thickness of epicuticle which is almost as thick as the procuticle in the papillate region and only about one sixth of the thickness of procuticle in the anterior chamber. The apical plasma membrane in both hindgut regions forms an apical plasma membrane labyrinth of cytoplasmic strands and extracellular spaces. In the papillate region the membranous infoldings are deeper and the extracellular spaces are wider. The basal plasma membrane is extensively infolded and associated with numerous mitochondria in the papillate region, while it forms relatively scarce basal infoldings in the anterior chamber. The junctional complex in both hindgut regions consists of adherens and septate junctions. Septate junctions are more extensive in the papillate region. Na+/K+-ATPase was located mostly in the apical plasma membranes in both hindgut regions. The ultrastructural features of hindgut cuticle are discussed in comparison to exoskeletal cuticle and to cuticles of other arthropod transporting epithelia from the perspective of their mechanical properties and permeability. The morphology of apical and basal plasma membranes and localisation of Na+/K+-ATPase are compared with other arthropod-transporting epithelia according to different functions of the anterior chamber and the papillate region.

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.

scholarly journals Crosstalk between basal extracellular matrix adhesion and building of apical architecture during morphogenesis

Biology Open ◽  
2021 ◽  
Vol 10 (11) ◽  
Author(s):  
Mariana Barrera-Velázquez ◽  
Luis Daniel Ríos-Barrera
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Cell Shape ◽  
Plasma Membranes ◽  
Tube Formation ◽  
Apical Plasma Membrane ◽  
Complex Structures ◽  
Apicobasal Polarity ◽  
Basal Plasma ◽  
Shape Changes

ABSTRACT Tissues build complex structures like lumens and microvilli to carry out their functions. Most of the mechanisms used to build these structures rely on cells remodelling their apical plasma membranes, which ultimately constitute the specialised compartments. In addition to apical remodelling, these shape changes also depend on the proper attachment of the basal plasma membrane to the extracellular matrix (ECM). The ECM provides cues to establish apicobasal polarity, and it also transduces forces that allow apical remodelling. However, physical crosstalk mechanisms between basal ECM attachment and the apical plasma membrane remain understudied, and the ones described so far are very diverse, which highlights the importance of identifying the general principles. Here, we review apicobasal crosstalk of two well-established models of membrane remodelling taking place during Drosophila melanogaster embryogenesis: amnioserosa cell shape oscillations during dorsal closure and subcellular tube formation in tracheal cells. We discuss how anchoring to the basal ECM affects apical architecture and the mechanisms that mediate these interactions. We analyse this knowledge under the scope of other morphogenetic processes and discuss what aspects of apicobasal crosstalk may represent widespread phenomena and which ones are used to build subsets of specialised compartments.

scholarly journals Transcytosis via the late endocytic pathway as a cell morphogenetic mechanism

2020 ◽  
Author(s):  
R Mathew ◽  
LD Rios-Barrera ◽  
P Machado ◽  
Y Schwab ◽  
M Leptin
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Basal Membrane ◽  
Endocytic Pathway ◽  
Apical Plasma Membrane ◽  
Tracheal System ◽  
Basal Plasma ◽  
Membrane Compartments ◽  
Membrane Growth ◽  
A Cell

AbstractPlasma membranes fulfil many physiological functions. In polarized cells, different membrane compartments take on specialized roles, each being allocated correct amounts of membrane. The Drosophila tracheal system, an established tubulogenesis model, contains branched terminal cells with subcellular tubes formed by apical plasma membrane invagination. We show that apical endocytosis and late endosome-mediated trafficking determine the membrane allocation to the apical and basal membrane domains. Basal plasma membrane growth stops if endocytosis is blocked, whereas the apical membrane grows excessively. Plasma membrane is initially delivered apically, and then continuously endocytosed, together with apical and basal cargo. We describe an organelle carrying markers of late endosomes and multivesicular bodies (MVBs) that is abolished by inhibiting endocytosis, and which we suggest acts as transit station for membrane destined to be redistributed both apically and basally. This is based on the observation that disrupting MVB formation prevents growth of both compartments.

Fine Structure of Intestinal Epithelia of Earthworm

1972 ◽  
Vol 30 ◽  
pp. 174-175
Author(s):  
Brendan Clifford
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Lumbricus Terrestris ◽  
Apical Plasma Membrane ◽  
Straight Tube ◽  
Ultrastructural Investigation ◽  
Intestinal Epithelia ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Earthworm Gut

An ultrastructural investigation of the intestine of the earthworm, Lumbricus terrestris was undertaken as a part of a continuing study of absorptive epithelia.The earthworm gut is essentially a straight tube extending from gizzard to anus. The epithelia is an unicellular layer which can be regionally differentiated according to apical plasma membrane elaborations. The cells of the anterior 3/4 of the intestine possess microvilli and cilia (whose rootlets converge into bundles white approaching the basal plasma membrane). The cells of the dorsal typhlosole have microvilli but lack cilia while those of the posterior intestinal region possess microvilli, lack cilia and are covered by a well-defined cuticle through which the microvilli extend. The microvilli throughout the intestine (including those which extend through the posterior cuticle) are covered by a glycocalyx.

Alanine transport systems in isolated basal plasma membrane of human placenta

1989 ◽  
Vol 256 (3) ◽  
pp. C630-C637 ◽  
Author(s):  
S. D. Hoeltzli ◽  
C. H. Smith
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Plasma Membranes ◽  
Transport Systems ◽  
Acid Uptake ◽  
Plasma Membrane Vesicles ◽  
Basal Plasma Membrane ◽  
Sodium Dependent ◽  
Basal Plasma ◽  
System 2

Concentrative transfer of amino acids from mother to fetus is affected by transport across both microvillous (maternal-facing) and basal (fetal-facing) plasma membranes of the human placental syncytiotrophoblast. Isolated basal plasma membrane vesicles were used to elucidate transport systems for neutral amino acids across this membrane. The concentration dependence and inhibition of zero-trans-alanine uptake were studied and four pathways for alanine uptake were defined as follows: 1) a sodium-dependent system shared by methylaminoisobutyric acid, which has the characteristics of an A system; 2) a sodium-dependent system resistant to inhibition by methylaminoisobutyric acid, which has the characteristics of an ASC system; 3) a sodium-independent system which may resemble an L system; 4) nonsaturable uptake. The microvillous membrane of the syncytiotrophoblast possesses systems similar to 1 and 3, but system 2 is unique to the basal plasma membrane. Active and passive transport of amino acids across both microvillous and basal plasma membranes may contribute to trophoblast amino acid uptake and nutrition and to the transfer of amino acids to the fetus.

Differential localization of human nongastric H+-K+-ATPase ATP1AL1 in polarized renal epithelial cells

2000 ◽  
Vol 279 (3) ◽  
pp. F417-F425 ◽  
Author(s):  
Jürgen Reinhardt ◽  
Alexander V. Grishin ◽  
Hans Oberleithner ◽  
Michael J. Caplan
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Mdck Cells ◽  
Apical Plasma Membrane ◽  
Ion Pump ◽  
Β Subunit ◽  
Ion Pumps ◽  
Α Subunit ◽  
Renal Epithelial Cells

The human H+-K+-ATPase, ATP1AL1, belongs to the subgroup of nongastric, K+-transporting ATPases. In concert with the structurally related gastric H+-K+-ATPase, it plays a major role in K+ reabsorption in various tissues, including colon and kidney. Physiological and immunocytochemical data suggest that the functional heteromeric ion pumps are usually found in the apical plasma membranes of renal epithelial cells. However, the low expression levels of characteristic nongastric ion pumps makes it difficult to verify their spatial distribution in vivo. To investigate the sorting behavior of ATP1AL1, we expressed this pump by stable transfection in MDCK and LLC-PK1 renal epithelial cell lines. Stable interaction of ATP1AL1 with either the endogenous Na+-K+-ATPase β-subunit or the gastric H+-K+-ATPase β-subunit was tested by confocal immunofluorescence microscopy and surface biotinylation. In cells transfected with ATP1AL1 alone, the α-subunit accumulated intracellularly, consistent with its inability to assemble and travel to the plasma membrane with the endogenous Na+-K+-ATPase β-subunit. Cotransfection of ATP1AL1 with the gastric H+-K+-ATPase β-subunit resulted in plasma membrane localization of both pump subunits. In cotransfected MDCK cells the heteromeric ion pump was predominantly polarized to the apical plasma membrane. Functional expression of ATP1AL1 was confirmed by 86Rb+uptake measurements. In contrast, cotransfected LLC-PK1cells accumulate ATP1AL1 at the lateral membrane. The distinct polarization of ATP1AL1 indicates that the α-subunit encodes sorting information that is differently interpreted by cell type-specific sorting mechanisms.

Active Transport of Potassium by the Cecropia Midgut

1969 ◽  
Vol 50 (1) ◽  
pp. 169-178
Author(s):  
J. L. WOOD ◽  
P. S. FARRAND ◽  
W. R. HARVEY
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Active Transport ◽  
Plasma Membranes ◽  
Potassium Concentration ◽  
Equilibrium Potential ◽  
Apical Plasma Membrane ◽  
Electrogenic Pump ◽  
Positive Step ◽  
Two Barriers

1. The potential profile recorded as a microelectrode is advanced from the blood side through the isolated midgut of Hyalophora cecropia consists of negative plateaus followed by a large positive step to the full midgut potential. 2. Oxygen deprivation diminishes both the positive step and the midgut potential; the negative plateaus are not affected. 3. Changes in the potassium concentration in the blood-side solution affect both the negative plateaus and the midgut potential; the large positive step remains about the same. 4. From these results it is concluded that the positive step is probably produced by the electrogenic potassium pump and that the negative steps are due to a potassium equilibrium potential. 5. The discrete and independent nature of the negative and positive potentials argues that there are two barriers separating a ‘midgut’ compartment from the two bathing solutions. 6. It is inferred that the epithelial cells are the site of the profile negativity and therefore that they constitute the ‘midgut’ compartment. This interpretation implies that the potassium equilibrium potential appears across the basal cell membranes and that electrogenic pump potential appears across the apical plasma membranes of the epithelial cells. 7. The most conservative interpretation of these results is that the electrogenic potassium pump is located somewhere in or on the apical plasma membrane of the epithelial cells.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

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