scholarly journals Differentiated microdomains on the luminal surface of the capillary endothelium. I. Preferential distribution of anionic sites.

1981 ◽  
Vol 90 (3) ◽  
pp. 605-613 ◽  
Author(s):  
N Simionescu ◽  
M Simionescu ◽  
G E Palade
Keyword(s):  
Distribution Pattern ◽  
Capillary Endothelium ◽  
Similar Distribution ◽  
Coated Pits ◽  
Free Aldehyde ◽  
Functional Implications ◽  
Aldehyde Groups ◽  
Similar Distribution Pattern

Cationized ferritin (CF), introduced systemically in vivo or by perfusion in situ, binds preferentially to certain microdomains of the luminal plasmalemma of fenestrated capillaries (mouse pancreas and jejunum). The density and affinity of binding decrease in the following order: fenestral diaphragms greater than coated pits greater than plasmalemma proper. CF binds neither to the membrane of plasmalemmal vesicles and transendothelial channels nor to the corresponding stomatal diaphragms. The distribution pattern is the same when glutaraldehyde fixation precedes the administration of the tracer by perfusion, provided fixation is followed by quenching of residual free aldehyde groups. A much smaller cationic probe (alcian blue) perfused together with the fixative reveals a similar distribution pattern. The functional implications of the association of these microdomains with structures involved in capillary permeability are discussed.

scholarly journals Neural Differentiation in HDAC1-Depleted Cells Is Accompanied by Coilin Downregulation and the Accumulation of Cajal Bodies in Nucleoli

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jana Krejčí ◽  
Soňa Legartová ◽  
Eva Bártová
Keyword(s):  
Distribution Pattern ◽  
Neural Differentiation ◽  
Adult Mouse ◽  
Embryonic Stem ◽  
Adult Brain ◽  
Cajal Bodies ◽  
Similar Distribution ◽  
Nuclear Events ◽  
Adult Hippocampus ◽  
Similar Distribution Pattern

Cajal bodies (CBs) are important compartments containing accumulated proteins that preferentially regulate RNA-related nuclear events, including splicing. Here, we studied the nuclear distribution pattern of CBs in neurogenesis. In adult brains, coilin was present at a high density, but CB formation was absent in the nuclei of the choroid plexus of the lateral ventricles. Cells of the adult hippocampus were characterized by a crescent-like morphology of coilin protein. We additionally observed a 70 kDa splice variant of coilin in adult mouse brains, which was different to embryonic brains and mouse pluripotent embryonic stem cells (mESCs), characterized by the 80 kDa standard variant of coilin. Here, we also showed that depletion of coilin is induced during neural differentiation and HDAC1 deficiency in mESCs caused coilin accumulation inside the fibrillarin-positive region of the nucleoli. A similar distribution pattern was observed in adult brain hippocampi, characterized by lower levels of both coilin and HDAC1. In summary, we observed that neural differentiation and HDAC1 deficiency lead to coilin depletion and coilin accumulation in body-like structures inside the nucleoli.

Role of blood pressure in mediating the influence of salt intake on renin expression in the kidney

2012 ◽  
Vol 302 (10) ◽  
pp. F1278-F1285 ◽  
Author(s):  
Katharina Machura ◽  
Björn Neubauer ◽  
Dominik Steppan ◽  
Ramona Kettl ◽  
Andreas Groβ ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Distribution Pattern ◽  
Salt Intake ◽  
Salt Content ◽  
Similar Distribution ◽  
High Salt Intake ◽  
Low Salt ◽  
Afferent Arterioles ◽  
Similar Distribution Pattern

The salt intake of an organism controls the number of renin-producing cells in the kidney by yet undefined mechanisms. This study aimed to assess a possible mediator role of preglomerular blood pressure in the control of renin expression by oral salt intake. We used wild-type (WT) mice and mice lacking angiotensin II type 1a receptors (AT1a−/−) displaying an enhanced salt sensitivity to renin expression. In WT kidneys, we found renin-expressing cells at the ends of all afferent arterioles. A low-salt diet (0.02%) led to a moderate twofold increase in renin-expressing cells along afferent arterioles. In AT1a−/− mice, lowering of salt content led to a 12-fold increase in renin expression. Here, the renin-expressing cells were distributed along the preglomerular vascular tree in a typical distal-to-proximal distribution gradient which was most prominent at high salt intake and was obliterated at low salt intake by the appearance of renin-expressing cells in proximal parts of the preglomerular vasculature. While lowering of salt intake produced only a small drop in blood pressure in WT mice, the marked reduction of systolic blood pressure in AT1a−/− mice was accompanied by the disappearance of the distribution gradient from afferent arterioles to arcuate arteries. Unilateral renal artery stenosis in AT1a−/− mice on a normal salt intake produced a similar distribution pattern of renin-expressing cells as did low salt intake. Conversely, increasing blood pressure by administration of the NOS inhibitor N-nitro-l-arginine methyl ester or of the adrenergic agonist phenylephrine in AT1a−/− mice kept on low salt intake produced a similar distribution pattern of renin-producing cells as did normal salt intake alone. These findings suggest that changes in preglomerular blood pressure may be an important mediator of the influence of salt intake on the number and distribution of renin-producing cells in the kidney.

scholarly journals Rat glomerular epithelial cells in culture express characteristics of parietal, not visceral, epithelium.

1992 ◽  
Vol 3 (6) ◽  
pp. 1279-1287
Author(s):  
T Weinstein ◽  
R Cameron ◽  
A Katz ◽  
M Silverman
Keyword(s):  
Epithelial Cells ◽  
Intermediate Filaments ◽  
Rat Kidney ◽  
Parietal Cells ◽  
Immunoperoxidase Staining ◽  
Puromycin Aminonucleoside ◽  
Coated Pits ◽  
Glomerular Epithelial Cells

Glomerular epithelial cells (GEC) in culture are derived from intact isolated glomeruli. Although there is general agreement about distinguishing GEC from mesangial and endothelial cells, there is still uncertainty regarding the visceral versus parietal origin of cultured GEC. If these cells are to provide a useful model system, it is necessary to establish well-defined cell populations. The purpose of this study was to evaluate this important issue by comparing the characteristics of cultured GEC with glomerular epithelium from rat kidney sections. By electron microscopy, GEC were polygonal, with cilia and desmosomes between cells, similar to parietal cells in situ. Because intermediate filaments are specifically expressed in differentiated cells in the kidney, the expression of intermediate filaments in cultured GEC were compared with those of intact glomeruli. Cultured GEC are positive for cytokeratin and negative for vimentin and desmin, identical to parietal cells in situ. In contrast, podocytes are positive for vimentin and desmin and negative for cytokeratin. In vivo, podocytes express gp330 and puromycin-aminonucleoside (PAN) susceptibility, which are used as markers for cultured GEC. Immunoperoxidase staining of rat kidney sections with monoclonal anti-gp330 demonstrated gp330 localization to the cell surface and coated pits of the parietal cells, similar to its localization in podocytes. The presence of gp330 in cultured GEC was confirmed by immunoblot. PAN administration to rats induced vacuolization and detachment from the basement membrane in the parietal cells of Bowman's capsule, similar to the cytotoxicity observed in podocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Trimeric binding of the 70-kD uncoating ATPase to the vertices of clathrin triskelia: a candidate intermediate in the vesicle uncoating reaction.

1989 ◽  
Vol 109 (4) ◽  
pp. 1457-1466 ◽  
Author(s):  
J Heuser ◽  
C J Steer
Keyword(s):  
Atp Hydrolysis ◽  
Bovine Brain ◽  
Coated Vesicles ◽  
Coated Pits ◽  
Experimental Conditions ◽  
Molecular Conformations ◽  
Product Release ◽  
Protein Polymer

Clathrin-coated vesicles were uncoated with the 70-kD "uncoating ATPase" from bovine brain, and the molecular products were visualized by freeze-etch electron microscopy. This yielded images of released clathrin triskelia with up to three 70-kD uncoating ATPase molecules bound to their vertices. Likewise, incubation of soluble clathrin triskelia with purified uncoating ATPase also led to trimeric binding of the ATPase to the vertices of clathrin triskelia. However, this occurred only when either EDTA or nonhydrolyzable analogues of ATP were present, in which case the ATPase also appeared to self-associate. When ATP was present instead, no 70-kD ATPases could be found on clathrin triskelia and all ATPases remained monomeric. These observations support the notion that ATP controls an allosteric conversion of the 70-kD uncoating ATPase between two different molecular conformations, an ATP-charged state in which the molecule has relatively low affinity for itself as well as low affinity for clathrin, and an ATP-discharged state in which both of these affinities are high. We presume that in vivo, the latter condition is brought about by ATP hydrolysis and product release, at which point the ATPase will bind tightly to clathrin and/or self-associate. We further propose that these reactions, when occurring in concert within a clathrin lattice, will tend to destabilize it by a mechanism we call "protein polymer competition". We stress the analogies between such a mechanism of uncoating and the ATP-driven events in muscle contraction. Finally, we show that under experimental conditions in which the uncoating ATPase fully removes the coats from brain coated vesicles, identical aliquots of the enzyme do not affect plasmalemmal coated pits in situ. This remarkable selectivity, the mechanism of which remains a complete mystery, is at least consistent with the idea that the 70-kD ATPase indeed plays a role in uncoating coated vesicles after they have formed in vivo.

scholarly journals Differentiated microdomains on the luminal surface of the capillary endothelium. II. Partial characterization of their anionic sites.

1981 ◽  
Vol 90 (3) ◽  
pp. 614-621 ◽  
Author(s):  
M Simionescu ◽  
N Simionescu ◽  
J E Silbert ◽  
G E Palade
Keyword(s):  
Binding Sites ◽  
Chemical Nature ◽  
Capillary Endothelium ◽  
Anionic Sites ◽  
Coated Pits ◽  
Chondroitinase Abc ◽  
Mouse Pancreas ◽  
Broad Specificity

To investigate the chemical nature of the cationic ferritin (CF)-binding sites of the differentiated microdomains of the capillary endothelium, the vasculature of the mouse pancreas and intestinal mucosa was perfused in situ with neuraminidase, hyaluronidase, chondroitinase ABC, heparinase, and three proteases: trypsin, papain, and pronase. Proteases of broad specificity removed all anionic sites, suggesting that the latter are contributed by acid glycoproteins or proteoglycans. Neuraminidase, hyaluronidase, and chondroitinase ABC reduced the density of CF-binding sites on the plasmalemma proper, but had no effect on either coated pits or fenestral diaphragms. Heparinase removed CF-binding sites from fenestral diaphragms and had no effect on coated pits. Taken together, these results indicate that the anionic sites of the fenestral diaphragms are contributed primarily by heparan sulfate and/or heparin, whereas those of the plasmalemma proper are of mixed chemical nature. The membranes and diaphragms of plasmalemmal vesicles and transendothelial channels do not bind CF in control specimens; this condition is not affected by the enzymic treatments mentioned above.

scholarly journals Recent shallow marine Ostracoda of the Ikerssuak (Bredefjord) District, Southwest Greenland

1989 ◽  
Vol 8 (1) ◽  
pp. 55-75 ◽  
Author(s):  
David N. Penney
Keyword(s):  
Primary Production ◽  
Distribution Pattern ◽  
Late Summer ◽  
Similar Distribution ◽  
Western Atlantic ◽  
Shallow Marine ◽  
The Town ◽  
Similar Distribution Pattern ◽  
Ostracod Species ◽  
Southwest Greenland

Abstract. From a study of 15 grab samples collected from the littoral and sublittoral of the Ikerssuak (Bredefjord) district, SW Greenland, one myodocopid and 18 podocopid ostracod species were recovered. These constitute an indigenous fauna and the majority have been recorded from Greenland before. Leptocythere castanea and Leptocythere lacertosa are new to Greenland, and have not previously been confirmed from the western Atlantic. Copulating pairs of Hemicythere borealis were found in an intertidal embayment near the town of Narssaq. This species reproduced just before the late summer-autumn maximum of primary production in the area, and at the warmest time of the year. Semicytherura nigrescens, which has been recorded previously in SW Greenland, may have a similar distribution pattern to certain Subarctic Mollusca in western Greenland.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Sinusoidal Cells in Bone Marrow Take Up BSA-Au Conjugates in the Presence of an Artificial Blood Substitute

1985 ◽  
Vol 43 ◽  
pp. 700-701
Author(s):  
J.S. Geoffroy ◽  
R.P. Becker
Keyword(s):  
Bone Marrow ◽  
Los Angeles ◽  
Iliac Artery ◽  
Blood Substitute ◽  
Sprague Dawley ◽  
Coated Pits ◽  
Sinusoidal Cells ◽  
Artificial Blood ◽  
Left Common Iliac Artery

The pattern of BSA-Au uptake in vivo by endothelial cells of the venous sinuses (sinusoidal cells) of rat bone marrow has been described previously. BSA-Au conjugates are taken up exclusively in coated pits and vesicles, enter and pass through an “endosomal” compartment comprised of smooth-membraned tubules and vacuoles and cup-like bodies, and subsequently reside in multivesicular and dense bodies. The process is very rapid, with BSA-Au reaching secondary lysosmes one minute after presentation. (Figure 1)In further investigations of this process an isolated limb perfusion method using an artificial blood substitute, Oxypherol-ET (O-ET; Alpha Therapeutics, Los Angeles, CA) was developed. Under nembutal anesthesia, male Sprague-Dawley rats were laparotomized. The left common iliac artery and vein were ligated and the right iliac artery was cannulated via the aorta with a small vein catheter. Pump tubing, preprimed with oxygenated 0-ET at 37°C, was connected to the cannula.

Three-Dimensional Subcellular Organization of Hepatocytes in Intact Liver: Simultaneous Visualization of Cytoskeletal and Membrane Markers by Confocal Microscopy

1996 ◽  
Vol 54 ◽  
pp. 288-289
Author(s):  
Greg V. Martin ◽  
Ann L. Hubbard
Keyword(s):  
Three Dimensional ◽  
Integral Membrane Proteins ◽  
Polarized Secretion ◽  
Microscope Images ◽  
Computer Aided ◽  
Intracellular Organelles ◽  
Cytoskeletal Elements ◽  
Simultaneous Visualization

The microtubule (MT) cytoskeleton is necessary for many of the polarized functions of hepatocytes. Among the functions dependent on the MT-based cytoskeleton are polarized secretion of proteins, delivery of endocytosed material to lysosomes, and transcytosis of integral plasma membrane (PM) proteins. Although microtubules have been shown to be crucial to the establishment and maintenance of functional and structural polarization in the hepatocyte, little is known about the architecture of the hepatocyte MT cytoskeleton in vivo, particularly with regard to its relationship to PM domains and membranous organelles. Using an in situ extraction technique that preserves both microtubules and cellular membranes, we have developed a protocol for immunofluorescent co-localization of cytoskeletal elements and integral membrane proteins within 20 µm cryosections of fixed rat liver. Computer-aided 3D reconstruction of multi-spectral confocal microscope images was used to visualize the spatial relationships among the MT cytoskeleton, PM domains and intracellular organelles.

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