Lysolecithin Induced Membrane Alterations in Thymocytes

1975 ◽  
Vol 30 (11-12) ◽  
pp. 785-792 ◽  
Author(s):  
Hans Ulrich Weltzien
Keyword(s):  
Immune Response ◽  
Concanavalin A ◽  
Lectin Binding ◽  
Inhibitory Effect ◽  
Short Chain ◽  
Membrane Properties ◽  
Con A ◽  
Lectin Receptors ◽  
Induced Membrane ◽  
Kinetics Of

Abstract The effects of lysolecithin and of 2 synthetic ether-desoxy lysolecithin analogs, containing alkyl residues of 16 or 12 carbon atoms, on the agglutination kinetics of calf and rabbit thymocytes by concanavalin A (Con A) were investigated. Unlike the natural lysolecithin, these synthetic analogs are resistant to metabolism by membrane associated enzymes. It was found that pretreatment of thymocytes with lysolecithin or with the C16-analog leads to slightly increased agglutination rates. The C12-analog, in contrast, significantly inhibits thymocyte agglutination by Con A. More­ over, a comparison of these results with lysophosphatide effects on the agglutinability of erythrocytes of various species revealed that the inhibitory effect of the short-chain phosphatide is rather specific for thymocytes. The finding that long-and short-chain lysophosphatides, which have previously been shown to react as adjuvants or immunosuppressants, respectively, induce adserve alterations in thymocyte membranes indicates that these substances may affect the immune response by changing the membrane properties of immune competent cells. Concerning the nature of these membrane alterations it was shown that lysolecithin did not affect the number of Con A receptors per cell nor the affinity of lectin binding. It is therefore concluded that the lysophosphatide in­ duced alterations of Con A agglutinability can not be caused by an uncovering or covering of lectin-receptors.

Effect of bradykinin on membrane properties of guinea pig bronchial parasympathetic ganglion neurons

2000 ◽  
Vol 278 (3) ◽  
pp. L485-L491 ◽  
Author(s):  
Radhika Kajekar ◽  
Allen C. Myers
Keyword(s):  
Guinea Pig ◽  
Sensory Nerve ◽  
Input Resistance ◽  
Inhibitory Effect ◽  
Membrane Properties ◽  
Alternative Mechanism ◽  
Induced Membrane ◽  
Parasympathetic Ganglion ◽  
Hoe 140 ◽  
Ganglion Neurons

The effect of bradykinin on membrane properties of parasympathetic ganglion neurons in isolated guinea pig bronchial tissue was studied using intracellular recording techniques. Bradykinin (1–100 nM) caused a reversible membrane potential depolarization of ganglion neurons that was not associated with a change in input resistance. The selective bradykinin B2 receptor antagonist HOE-140 inhibited bradykinin-induced membrane depolarizations. Furthermore, the cyclooxygenase inhibitor indomethacin attenuated bradykinin-induced membrane depolarizations to a similar magnitude (∼70%) as HOE-140. However, neurokinin-1 and -3 receptor antagonists did not have similar inhibitory effects. The ability of bradykinin to directly alter active properties of parasympathetic ganglion neurons was also examined. Bradykinin (100 nM) significantly reduced the duration of the afterhyperpolarization (AHP) that followed four consecutive action potentials. The inhibitory effect of bradykinin on the AHP response was reversed by HOE-140 but not by indomethacin. These results indicate that bradykinin can stimulate airway parasympathetic ganglion neurons independent of sensory nerve activation and provide an alternative mechanism for regulating airway parasympathetic tone.

scholarly journals Immunogold study on lectin binding in the porcine zona pellucida and granulosa cells

10.4081/846 ◽  
2009 ◽  
Vol 47 (4) ◽  
pp. 353 ◽  
Author(s):  
F Parillo ◽  
C Dall’Aglio ◽  
A Verini Supplizi ◽  
P Ceccarelli ◽  
AM Gargiulo
Keyword(s):  
Sialic Acid ◽  
Horseradish Peroxidase ◽  
Granulosa Cells ◽  
Zona Pellucida ◽  
Lectin Binding ◽  
Protein A ◽  
Ultrastructural Localization ◽  
Binding Pattern ◽  
Con A ◽  
Lectin Receptors

An ultrastructural localization of lectin receptors on the zona pellucida (ZP) of porcine antral oocytes and on the granulosa cells was performed using a panel of horseradish peroxidase- labelled lectins in conjunction with antiperoxidase antibody and protein A-gold. In some cases, lectin incubation was preceded by sialidase digestion. WGA-, Con-A-, UEA-I-, RCA-I-, PNA- and SBA-reactive sites were distributed differently in the porcine ZP. Sialidase digestion increased the positivity obtained with RCA-I and it was necessary to promote PNA and SBA reactivity. These results indicated that the ZP contained N-acetylglucosamine, a-mannose, a- fucose, b-Gal-(1-4)GlcNAc, b-Gal- (1-3)GalNAc, b-GalNAc and sialic acid residues. We also observed the presence of vesicles in both the ooplasm and granulosa cells, showing a similar lectin binding pattern to that of the ZP, thus suggesting that the oocyte and granulosa cells are the site of synthesis of ZP glucidic determinants.

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 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 Surface properties related to concanavalin A-induced agglutination. A comparative study of several Entamoeba strains.

1977 ◽  
Vol 145 (3) ◽  
pp. 652-665 ◽  
Author(s):  
D Trissl ◽  
A Martínez-Palomo ◽  
C Argüello ◽  
M de la Torre ◽  
R de la Hoz
Keyword(s):  
Surface Properties ◽  
Concanavalin A ◽  
Room Temperature ◽  
Lectin Binding ◽  
Cationized Ferritin ◽  
Con A ◽  
Low Concentrations ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Axenic Strains

Pathogenic strains of Entamoeba histolytica are more easily agglutinated with concanavalin A (Con A) than strains isolated from human asymptomatic carriers. All three pathogenic strains studied here were found to agglutinate with low concentrations of Con A in contrast to various nonpathogenic axenic strains of amebas, characterized by their ability to grow at room temperature. Our present observations suggest that the extreme susceptibility of pathogenic strains of E. histolytica to agglutinate with Con A is related to their higher capacity for lectin binding and to their lack of detectable repulsive charges at the cell surface. The amount of fluorescein-tagged Con A bound to the surface was much higher in pathogenic strains. Only nonpathogenic strains showed a detectable negative surface charge as studied both by means of cell microelectrophoresis and by labeling cells with cationized ferritin at 0 degrees C. The mobility of surface Con A receptors estimated as the percentage of caps was comparable in all strains. Results of one strain cultured in axenic and monoxenic conditions suggested that bacteria can modify the behaviour of E. histolytica trophozoites by altering surface properties of the amebas.

Lectin Binding Demonstrates Different Glycoprotein Abnormalities In Thrombasthenic And Bernard-Soulier Platelets

1981 ◽  
Author(s):  
Philip A Judson ◽  
David J Anstee
Keyword(s):  
Arachis Hypogaea ◽  
Concanavalin A ◽  
Marked Reduction ◽  
Human Platelet ◽  
Lectin Binding ◽  
Minor Components ◽  
Polyacrylamide Gels ◽  
Con A ◽  
Platelet Membranes ◽  
Bernard Soulier Syndrome

We have previously shown that the lectins from Maclura aurantiaca (Ma) and Arachis hypogaea (Ah) (peanut) bind selectively to GP-I in human platelet membranes. In contrast Concanavalin A lectin binds primarily to GP-III. GP-I is deficient or absent from the membranes of individuals with Bernard-Soulier Syndrome (B-S.S.) while GP-II and III are deficient or absent from Thrombasthenic (G.T.) platelets. We have investigated the binding of radioiodinated lectins to SDS polyacrylamide gels of whole platelets from patients with B-S.S. and G.T. The object of this study was to define further the nature of the glycoprotein abnormalities in these conditions.The results clearly demonstrated a marked reduction in the binding of Ma and Ah lectins to the GP-I region of B-S platelets when compared to that of normal platelets. No new lectin binding components were observed. The binding of Con A lectins to B-S platelets did not appear to be significantly different from that to normal platelets. In contrast Ma and Ah binding to G.T. platelets appeared normal whereas the binding of Con A to GP-III was markedly reduced. Two faint Con A binding bands were apparent in the GP-III region of the G.T. platelets. It is not clear whether either of these represent residual GP-III or if they are minor components masked by GP-III in normal platelets. The carbohydrate of GP-I in normal platelets consists almost entirely of O-glycosidically linked oligosaccharides. Ah and Ma lectins bind selectively to galactosyl and N-acetylgalactosaminyl residues in this type of oligosaccharide. We conclude that B-S platelets have a gross deficiency of O-glycosidically linked oligosaccharides. Con A binds selectively to branched N-glycosidically linked oligosaccharides with a mannose-rich core. We conclude that such structures normally present on GP-III are grossly deficient in G.T. platelets.

scholarly journals Estrogen-induced membrane alterations and growth associated with proteinase activity in endometrial cells.

1979 ◽  
Vol 81 (3) ◽  
pp. 649-663 ◽  
Author(s):  
R J Pietras ◽  
C M Szego
Keyword(s):  
Specific Binding ◽  
Prior Treatment ◽  
Proteinase Activity ◽  
Membrane Properties ◽  
Ovariectomized Rats ◽  
Con A ◽  
Intact Cells ◽  
Pronounced Increase ◽  
Induced Membrane ◽  
Endometrial Cells

Endometrial cells isolated from uteri of ovariectomized rats were treated in vitro with 1 X 10(-9) M estradiol-17 beta (E2beta) to analyze early changes in membrane properties during hormone-induced growth. After 30-min exposure to E2beta at 22 degrees C, cells exhibited an enhanced capacity to bind erythrocytes (hemadsorption) in the presence of concanavalin A (Con A) to 237% of the level in paired controls. Fluorescence microscopy revealted that approximately 25% of cells exposed to E2beta, but not estradiol-17 alpha (E2alpha), showed a redistribution into polar clusters of Con A-binding sites that were dispersed in random patches at the external surfaces of control cells. These hormore-induced membrane alterations were abolished by prior treatment of cells with inhibitors of thiol proteinase activity of the cathepsin B1 (CB1) type, such as leupeptin and iodoacetate. Leupeptin at 4.5 X 10(-7) M also reduced the affinity of [3H]E2beta binding to intact cells but did not influence specific binding of the hormone to macromolecular components of cytosol. A pronounced increase in the availability of endogenous CB1, But not of alkaline phosphatase, succinate, or lactate dehydrogenase, in the extracellular media was elicited within 30 min after E2beta treatment. In cells cultured in chemically defined medium for up to 48 h, E2beta, but not E2alpha, enhanced cell proliferation and stimulated [3H]thymidine incorporation into macromolecular form. These E2beta-induced effects were abolished by prior treatment of cells with liposome-entrapped leupeptin at a final concentration of 7 X 10(-8) M. The net rate of intercellular adhesion among endometrial cells was also enhanced by E2beta. This hormonal response was diminished by prior exposure to leupeptin. Fractionation of cells by selection for adhesiveness due to E2beta exposure for 30 min yielded a subpopulation of rapidly dividing cells which surpassed their less adhesive counterparts in cathepsin secretion and in Con A-mediated hemadsorption. These results indicate that leupeptin-sensitive proteinase activity may contribute to membrane and growth modifications elicited by E2beta treatment in endometrial cells.

Concanavalin A binding to amphibian embryo and effect on morphogenesis

Development ◽  
1979 ◽  
Vol 51 (1) ◽  
pp. 63-72
Author(s):  
J. C. Boucaut ◽  
B. Bernard ◽  
M. Aubery ◽  
R. Bourrillon ◽  
Ch. Houillon
Keyword(s):  
Concanavalin A ◽  
Direct Interaction ◽  
Fluorescein Isothiocyanate ◽  
Inhibitory Effect ◽  
Vitelline Membrane ◽  
Con A ◽  
Amphibian Embryo ◽  
Before And After ◽  
Three Stages ◽  
Pleurodeles Waltlii

The effect of Concanavalin A (Con A) on morphogenesis in Pleurodeles waltlii has been studied. Embryos were incubated with various concentrations of the lectin for a period of 6 days. Three stages of development were examined, late blastula, young gastrula and late gastrula. In the presence of the lectin at a concentration of 200, 150 or 100 μg/ml morphogenic movements were delayed, altered and finally blocked. At lower concentrations, 50 or 25 μg/ml, there was a slight delay in gastrulation, but in some cases development was normal. These findings indicate that Con A exerted an inhibitory effect on amphibian morphogenesis and there is evidence that the lectin effect was concentration dependent. The effects of Con A were specific since they were totally inhibited by α-methyl-D-mannopyranoside (0·05 m). The viability of the 24 h lectin-treated embryos was demonstrated by washing experiments. Labelled Con A binding to the embryos was investigated before and after discarding the vitelline membrane. The results suggest a direct interaction between Con A and the cell surface and this was confirmed by using fluorescein isothiocyanate Con A.

The relationship between endocytosis of concanavalin A and phytohaemagglutinin receptors and blast transformation, and direct identification of individual rabbit lymphocytes reactive to both mitogens

1982 ◽  
Vol 56 (1) ◽  
pp. 141-156
Author(s):  
C. Raffel ◽  
S. Sell
Keyword(s):  
Cell Surface ◽  
Concanavalin A ◽  
Cell Activation ◽  
Lectin Binding ◽  
Lymphocyte Activation ◽  
Early Event ◽  
Blast Transformation ◽  
Lectin Receptors ◽  
Surface Receptors ◽  
Rabbit Lymphocytes

Distribution and modulation of rabbit lymphocyte phytohaemagglutinin acceptors and concanavalin A acceptors during activation of rabbit lymphocytes have been examined by electron microscopy. Two types of cell surface acceptors have been tentatively identified, lectin binding acceptors that do not modulate, and receptors that are endocytosed when blast transformation is stimulated. All of the cells have binding acceptors for both lectins. Endocytosis correlates with early blast transformation and serves as an early marker for lymphocyte activation. When examined after 24 h of culture, those cells that undergo blast transformation contain endocytosed lectin receptors, whereas small untransformed cells do not. Capping prior to endocytosis is rarely observed. The mechanism whereby the signal for transformation is maintained after the reaction of lectin with cell surface receptors and transposed to the nucleus is not known. Although we conclude that endocytosis is an early event required for cell activation, it is possible that endocytosis is secondary to other activation events. By evaluation of sequential endocytosis, individual rabbit lymphocytes that endocytose only concanavalin A, only phytohaemagglutinin, both concanavalin A and phytohaemagglutinin, or neither lectin, have been identified.

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