scholarly journals Schistosomula of Schistosoma mansoni clear concanavalin A from their surface by sloughing.

1982 ◽  
Vol 94 (2) ◽  
pp. 355-362 ◽  
Author(s):  
J C Samuelson ◽  
J P Caulfield ◽  
J R David
Keyword(s):  
Schistosoma Mansoni ◽  
Concanavalin A ◽  
Binding Sites ◽  
Culture Medium ◽  
Culture Media ◽  
Lectin Binding ◽  
Defined Medium ◽  
Con A ◽  
Sds Page ◽  
Lectin Binding Sites

The lectin concanavalin A (Con A) was used as a model probe to study the behavior of molecules bound to the surface of recently transformed schistosomula of Schistosoma mansoni. Con A binding was saturable (150-180 pg/organism) and specifically competed by alpha-methyl mannoside. Both FITC-Con A and 125-I-Con A were lost from the surface of schistosomula with a halftime of 8-10 h in culture in defined medium. A comparable decrease in the binding of Con A to schistosomula cultured and then labeled with the lectin indicated that the labeling procedure itself was not inducing the observed change. Internalization of Con A was not seen by either fluorescence microscopy or electron microscope radioautography. In addition, 70-80% of the radioactivity lost from the parasite was recoverable by TCA precipitation from the culture medium as intact Con A (27,000 mol wt on SDS PAGE). Thus, the mechanism of clearance of bound Con A from the surface of cultured schistosomula is apparently by sloughing of Con A molecules intact into the culture media and not by endocytosis and degradation. Con A binding sites, visualized with hemocyanin by scanning electron microscopy, appeared homogeneously distributed over the surface of schistosomula when organisms were labeled at 4 degree C or after fixation with glutaraldehyde. However, Con A and hemocyanin formed aggregates on the surface of schistosomula when labeling was performed at 37 degrees C, which suggests that lectin binding sites have lateral mobility within the plane of the membrane. These aggregates are likely independent of metabolism by the parasite because aggregation also occurs on the surface of organisms killed with azide.

scholarly journals Ultrastructural localization of lectin-binding sites on the zonae pellucidae and plasma membranes of mammalian eggs.

1975 ◽  
Vol 66 (2) ◽  
pp. 263-274 ◽  
Author(s):  
G L Nicolson ◽  
R Yanagimachi ◽  
H Yanagimachi
Keyword(s):  
Binding Sites ◽  
Plasma Membranes ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Ultrastructural Localization ◽  
Con A ◽  
Plasma Membrane Receptor ◽  
Rat Eggs ◽  
Mammalian Eggs ◽  
Lectin Binding Sites

Receptors for Ricinus communis agglutinin I (RCAI), concanavalin A (Con A), and wheat germ agglutinin (WGA) were localized on the zonae pellucidae and plasma membranes of hamster, mouse, and rat eggs with ferritin-lectin conjugates. Intact eggs labeled with the ferritin conjugates showed dense concentrations of RCAI and WGA receptors in the outermost regions of their zonae pellucidae and sparse distributions of Con A receptors throughout the zonae. Ferritin-lectin labeling was specific, since inhibitory saccharides effectively blocked labeling. The asymmetric density of RCAI receptors across the zona was confirmed by ferritin-RCAI and fluorescein-RCAI labeling of mechanically isolated zonae pellucidae, indicating that the RCAI-binding sites are more densely distributed in the exterior zona regions. Plasma membranes of rodent eggs contained RCAI, WGA, and Con A receptors. These receptors were found to be more or less randomly distributed on surfaces of aldehyde-fixed eggs or on eggs labeled near 0 degrees C. However, eggs incubated at 25 degrees C showed aggregated WGA- and Con A-binding site distributions on their plasma membranes. This indicates that lectin-induced receptor redistribution occurs at this temperature. The possibility that plasma membrane receptor mobility is a requirement for sperm-egg fusion is discussed.

scholarly journals Distribution of concanavalin A binding sites on the surface of dissociated rat submandibular gland acinar cells.

1975 ◽  
Vol 23 (8) ◽  
pp. 607-617 ◽  
Author(s):  
T Amakawa ◽  
T Barka
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Concanavalin A ◽  
Binding Sites ◽  
Lectin Binding ◽  
Single Cells ◽  
Apical Cell ◽  
Acinar Cells ◽  
Con A ◽  
Dissociated Cells

The submandibular glands of 4-week-old rats were dissociated by a procedure involving digestions with collagenase and hyaluronidase, chelation of divalent cations and mechanical force. A suspension of single cells was obtained in low yield by centrifugation in a Ficoll-containing medium. Immediately after dissociation and after a culture period of 16-18 hr the dissociated cells were tested for agglutinability by concanavalin A (Con A). Using ferritin (tfer)-conjugated Con A the lectin binding by the isolated acinar cells was also studied. The dissociated cells were agglutinated by low concentrations of Con A and bound Fer-Con A molecules on their entire surface without any indication of polarization of the cell membrane. There was a considerable cell to cell variation in the amount of Fer-Con A binding which was, in general, sparse and patchy. The contact surfaces between agglutinated cells revealed a dense binding of Fer-Con A molecules irrespective of the types of cells participating in the agglutination reaction. Cells cultured for 16-18 hr were no longer agglutinated by Con A. As compared to the freshly dissociated cells the cultured acinar cells revealed a more uniform and denser binding of Fer-Con A molecules. Furthermore, there were more lectin molecules bound to the cell surface corresponding to the basal part of the cell, where the nucleus and most of the rough surface endoplasmic reticulum were located, than to the apical cell surface. It is suggested that the higher density of lectin-binding sites on the cell surface in the vicinity of the cisternae of the rough endoplasmic reticulum indicates insertion sites of newly synthesized membrane glycoproteins.

scholarly journals Lectin-binding sites on the plasma membranes of rabbit spermatozoa: Changes in surface receptors during epididymal maturation and after ejaculation

1977 ◽  
Vol 74 (3) ◽  
pp. 950-962 ◽  
Author(s):  
GL Nicolson ◽  
N Usui ◽  
R Yanagimachi ◽  
H Yanagimachi ◽  
Smith JR
Keyword(s):  
Binding Sites ◽  
Plasma Membranes ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Similar Degree ◽  
Con A ◽  
Lectin Receptors ◽  
Surface Receptors ◽  
Epididymal Spermatozoa ◽  
Lectin Binding Sites

Modifications in rabbit sperm plasma membranes during epididymal passage and after ejaculation were investigated by used of three lectins: concanavalin A (Con A); Ricinus communis I (RCA(I)); and wheat germ agglutinin (WGA). During sperm passage from caput to cauda epididymis, agglutination by WGA drastically decreased, and agglutination by RCA(I) slightly decreased, although agglutination by Con A remained approximately unchanged. After ejaculation, spermatozoa were agglutinated to a similar degree or slightly less by Con A, WGA, and RCA(I), compared to cauda epididymal spermatozoa. Ultrastructural examination of sperm lectin-binding sites with ferritin- lectin conjugates revealed differences in the densities of lectin receptors in various sperm regions, and changes in the same regions during epididymal passage and after ejaculation. Ferritin-RCA(I) showed abrupt changes in lectin site densities between acrosomal and postacrosomal regions of sperm heads. The relative amounts of ferritin-RCA(I) bound to heads of caput epididymal or ejaculated spermatozoa. Tail regions were labeled by ferritin RCA(I) almost equally on caput and cauda epididymal spermatozoa, but the middle-piece region of ejaculated spermatozoa was slightly more densely labeled than the principal-piece region, and these two regions on ejaculated spermatozoa were labeled less than on caput and cuada epididymal spermatozoa. Ferritin-WGA densely labeled the acrosomal region of caput epididymal spermatozoa, although labeling of cauda epidiymal spermatozoa was relatively sparse except in the apical area of the acrosomal region. Ejaculated spermatozoa bound only a few molecules of ferritin-WGA, even at the highest conjugate concentrations used. Caput epididymal, but not cauda epididymal or ejaculated spermatozoa, bound ferritin-WGA in the tail regions. Dramatic differences in labeling densities during epididymal passage and after ejaculation were not found with ferritin-Con A.

scholarly journals Spatial orientation of glycoproteins in membranes of rat liver rough microsomes. I. Localization of lectin-binding sites in microsomal membranes.

1978 ◽  
Vol 78 (3) ◽  
pp. 874-893 ◽  
Author(s):  
E Rodriguez Boulan ◽  
G Kreibich ◽  
D D Sabatini
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Binding Sites ◽  
Microsomal Fraction ◽  
Lectin Binding ◽  
Membrane Glycoproteins ◽  
Con A ◽  
Microsomal Membranes ◽  
Carbohydrate Chains ◽  
Lectin Binding Sites

Carbohydrate-containing structures in rat liver rough microsomes (RM) were localized and characterized using iodinated lectins of defined specificity. Binding of [125I]Con A increased six- to sevenfold in the presence of low DOC (0.04--0.05%) which opens the vesicles and allows the penetration of the lectins. On the other hand, binding of [125I]WGA and [125I]RCA increased only slightly when the microsomal vesicles were opened by DOC. Sites available in the intact microsomal fraction had an affinity for [125I]Con A 14 times higher than sites for lectin binding which were exposed by the detergent treatment. Lectin-binding sites in RM were also localized electron microscopically with lectins covalently bound to biotin, which, in turn, were visualized after their reaction with ferritin-avidin (F-Av) markers. Using this method, it was demonstrated that in untreated RM samples, binding sites for lectins are not present on the cytoplasmic face of the microsomal vesicles, even after removal of ribosomes by treatment with high salt buffer and puromycin, but are located on smooth membranes which contaminate the rough microsomal fraction. Combining this technique with procedures which render the interior of the microsomal vesicles accessible to lectins and remove luminal proteins, it was found that RM membranes contain binding sites for Con A and for Lens culinaris agglutinin (LCA) located exclusively on the cisternal face of the membrane. No sites for WGA, RCA, soybean (SBA) and Lotus tetragonobulus (LTA) agglutinins were detected on either the cytoplasmic or the luminal faces of the rough microsomes. These observations demonstrate that: (a) sugar moieties of microsomal glycoproteins are exposed only on the luminal surface of the membranes and (b) microsomal membrane glycoproteins have incomplete carbohydrate chains without the characteristic terminal trisaccharides N-acetylglucosamine comes from galactose comes from sialic acid or fucose present in most glycoproteins secreted by the liver. The orientation and composition of the carbohydrate chains in microsomal glycoproteins indicate that the passage of these glycoproteins through the Golgi apparatus, followed by their return to the endoplasmic reticulum, is not required for their biogenesis and insertion into the endoplasmic reticulum (ER) membrane.

Surface structure of the golgi complex and identification of concanavalin-A binding sites

1978 ◽  
Vol 36 (2) ◽  
pp. 246-247
Author(s):  
J.M. Sturgess ◽  
M. Teitelman ◽  
M.A. Moscarello
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Golgi Complex ◽  
Concanavalin A ◽  
Binding Sites ◽  
Lectin Binding ◽  
Bicarbonate Buffer ◽  
Sodium Phosphate Buffer ◽  
Scanning Electron ◽  
Lectin Binding Sites

Scanning electron microscopy has been applied to study the surface ultrastructure of the Golgi complex and labelling techniques have been developed to investigate the distribution of lectin-binding sites on the membrane surfaces. The study is based on the examination of Golgi-rich fractions, isolated by homogenisation and differential centrifugation of rat liver. The membranes are fixed in suspension with 1% glutaraldehyde in 0.1 M sodium phosphate buffer, pH 7.4 for 60 mins and then rinsed in distilled water. For scanning electron microscopy, a thin film of membrane is frozen rapidly on coverglasses using liquid Freon 22, cooled by liquid nitrogen and dried in vacuo at -60°C. Membranes are coated with approximately 100 Å gold in a sputter coater and examined at 20 kV in a JEOL JSM-35U scanning electron microscope. For transmission electron microscopy, membranes are processed as described previously. For examination of lectin binding sites, isolated Golgi membranes are washed in sodium bicarbonate buffer, fixed in glutaraldehyde, incubated with concanavalin A (Con A), rinsed in buffer and then incubated with hemocyanin1.

scholarly journals Peroxidase and gold complexes of lectins for double labeling of surface-binding sites by electron microscopy.

1977 ◽  
Vol 25 (10) ◽  
pp. 1181-1184 ◽  
Author(s):  
J Roth ◽  
M Wagner
Keyword(s):  
Electron Microscopy ◽  
Horseradish Peroxidase ◽  
Concanavalin A ◽  
Binding Sites ◽  
Lectin Binding ◽  
Helix Pomatia ◽  
Surface Binding ◽  
Double Labeling ◽  
Membrane Bound ◽  
Lectin Binding Sites

Double labeling experiments were performed for visualization of the binding sites of Concanavalin A and anti-AHel (the lectin from Helix pomatia). The anti-AHel was labeled with the colloidal gold whereas the membrane bound Concanavalin A was demonstrated by an affinity technique using horseradish peroxidase. The two markers used could be clearly distinguished electron microscopically. The specificity of the cell surface double labeling was demonstrated in the control experiments. A topological distinct localization of the both lectin-binding sites is evident.

scholarly journals Binding of Concanavalin A to Rat, Normal Human, and Chronic Lymphatic Leukemia Lymphocytes

Blood ◽  
1972 ◽  
Vol 40 (3) ◽  
pp. 311-316 ◽  
Author(s):  
Abraham Novogrodsky ◽  
Miriam Biniaminov ◽  
Bracha Ramot ◽  
Ephraim Katchalski
Keyword(s):  
Dna Synthesis ◽  
Concanavalin A ◽  
Binding Sites ◽  
Lectin Binding ◽  
Chronic Lymphatic Leukemia ◽  
Con A ◽  
Lymphatic Leukemia ◽  
Maximal Stimulation ◽  
Normal Human ◽  
Stimulation Of

Abstract This study was aimed to find a correlation between the extent of concanavalin A (Con A) binding to lymphocytes and the blastogenic effect of the lectin on these cells. 63Ni-labeled Con A was used in the lectin-binding experiments. Binding of Con A to a small fraction (approximately 3%) of Con A binding sites in rat lymphocytes is required for the maximal stimulation of RNA synthesis. Binding of Con A to additional sites resulted in a less stimulatory effect. Lymphocytes from patients with chronic lymphatic leukemia (CLL) are impaired in their blastogenic response to Con A. Maximal stimulation of DNA synthesis induced by Con A in CLL lymphocytes is attained by treatment of the cells with the lectin at concentrations that are smaller than those required for the induction of maximal DNA synthesis in normal lymphocytes. The number of Con A binding sites in CLL lymphocyte is smaller than in normal lymphocyte.

Detection of glycoconjugates by lectins and glycosylated ferritin in the ciliary membrane of the quail oviduct

1978 ◽  
Vol 36 (2) ◽  
pp. 298-299
Author(s):  
Daniel Sandoz ◽  
Emmanuelle Boisvieux-Ulrich ◽  
Bernadette Chailley
Keyword(s):  
Binding Sites ◽  
Wheat Germ ◽  
External Surface ◽  
Lectin Binding ◽  
Good Resolution ◽  
Con A ◽  
Thin Sections ◽  
Ciliary Membrane ◽  
Wheat Germ Lectin ◽  
Lectin Binding Sites

The freeze-fractures of ciliary membrane show very few intramembrane particles except'for the ciliary necklace, located at the base of the organelle, which is composed of several sinuous arrays of particles (Fig.a). In the quail oviduct, it is also possible to distinguish these particles in thin sections, they appear as beads on the external surface of the ciliary membrane (Fig.b).Glycosylated ferritin allows the detection with a good resolution of the lectin binding sites of the plasma membrane.Pieces of quail oviduct (magnum) were incubated, after glutaralde- hyde fixation,either with Concanavaline A (major affinity : mannosyl or glucosyl residues), or wheat germ lectin (WGA)(major affinity : N-acetyl- glucosamine or N-acety1-neuraminic acid residues). The bound Con A molecules were visualized by Mannosyl-Ferritin. Control specimens were incubated directly with Mannosyl-Ferritin without prior incubation with Con A or with Con A in presence of 0-methyl-α -D-mannosyl-pyranoside.

Analysis of lectin- and snail plasma-binding glycopeptides associated with the tegumental surface of the primary sporocysts of Schistosoma mansoni

Parasitology ◽  
1996 ◽  
Vol 112 (5) ◽  
pp. 469-479 ◽  
Author(s):  
L. A. Johnston ◽  
T. P. Yoshino
Keyword(s):  
Schistosoma Mansoni ◽  
Binding Sites ◽  
Biomphalaria Glabrata ◽  
Plasma Binding ◽  
Con A ◽  
Tegumental Surface ◽  
Sds Page ◽  
Periodate Treatment ◽  
Molecular Masses ◽  
Surface Glycoproteins

SUMMARYCarbohydrates associated with the tegumental surface of Schistosoma mansoni primary sporocyst may serve as potential receptors for mediating recognition by the internal defence system of the molluscan host, Biomphalaria glabrata. Therefore, a combination of SDS-PAGE and lectin probe analyses were carried out on biotin-labelled tegumental glycopeptides as a first step to defining the carbohydrates expressed at the sporocyst surface. The majority of surface polypeptides, ranging in relative molecular masses from 27 to 113 kDa, reacted with horseradish peroxidase-labelled Canavalia ensiformis (Con A), Erythrina corallodendron (ECA), Glycine max (SBA) and Triticum vulgaris (WGA) lectins indicating that most, if not all, tegumental proteins are glycosylated. However, differences in the binding of some lectins to individual glycopeptides suggest a degree of heterogeneity in the structure/composition of sugar moieties comprising these surface glycoconjugates. This notion is supported by the finding that the fucose-specific Tetragonolobus purpureas (TPA) lectin only reacted with approximately 50% of glycopeptides identified at the tegumental surface. Experiments employing biotin-labelled plasma (cell-free haemolymph) from S. mansoni-susceptible and -resistant B. glabrata snails as probes, further demonstrated that many of the identified surface glycoproteins also serve as plasma-binding sites for both snail strains. Binding interactions between plasma and sporocyst surface glycoproteins appeared to be, at least in part, mediated by carbohydrates since periodate treatment of sporocyst proteins or pre-incubation of plasma with the glycoproteins, fetuin or mucin, resulted in a decrease in plasma reactivity to blotted larval proteins.

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