Trypanosoma rhodesiense Bloodstream Trypomastigote and Culture Procyclic Cell Surface Carbohydrates1, 2, 3

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diaminobenzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A < PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WGA, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M. The expression of lectin binding cell surface saccharides of T. rhodesiense WRATat 1 is related to the parasite stage. Sugars resembling α-D-mannose are on the surface of bloodstream trypomastigotes and culture procyclics; n-acetyl-D-galactosamine and D-galactose residues are on bloodstream forms; and n-acetyl-D-glucosamine-like sugars are on procyclic stages.     

Vitelline coat of Unio elongatulus: III. Glycan chain analysis of the 220- and 180-kD components by means of lectins

Lectins of different binding specificity were used to analyze the oligosaccharide chains of the 220- and 180-kD proteins of the Unio elongatulus egg vitelline coat (vc). The lectins ConA and RCA₁ reacted with both glycoproteins, and four other lectins reacted with one or other vc components. The lectin from Galanthus nivalis, which recognizes terminal mannose residues of N-linked high mannose type oligosaccharide chains, bound specifically to the 180-kD protein. Binding sites for this lectin were found throughout the vc of the differentiating oocyte and the mature egg. Lectins specific for the O-linked oligosaccharide chains, such as AIA and PNA, reacted only with the 220-kD protein species. Binding sites for these lectins were found only in the crater region. The presence of fucosyl residues on the glycan chains was investigated with lectins from Lotus tetragonolobus and Aleuria aurantia. The latter was positive on both glycoproteins, whereas LTA was only positive to the 220-kD species. The binding sites of both these lectins were in the same areas as those of PNA and AIA. These results suggest that while the 180-kD protein is part of the entire vc structure, the 220-kD protein is prevalently accumulated in the crater region. Since this is where sperm recognition and interaction take place, it has been suggested the 220-kD protein acts as a ligand molecule in the sperm-egg interaction. © 1995 Wiley-Liss, Inc.     

Trypanosoma rhodesiense bloodstream trypomastigote and culture procyclic cell surface carbohydrates

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRAT at 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diamino-benzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A greater than PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WAG, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interactions of lectins with plasma membrane glycoproteins of the Ehrlich ascites carcinoma cell

Several aspects of the interaction of various lectins with the surface of Ehrlich ascites carcinoma cells are described. The order of agglutinating activity for various various lectins is Ricinuscommunis > wheat germ concanavalin A soybean >Limuluspolyphemus. No agglutination was noted for Ulex europaeus. Using ¹²⁵I-labeled lectins it was determined that there are 1.6 and 7 times as many Ricinus communis lectin binding sites as sites for concanavalin A and soybean lectins. Sodium deoxy-cholate-solubilized plasma membrane material was subjected to lectin affinity chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The lectin receptors of the plasma membrane appeared to be heterogeneous and some qualitative differences could be discerned among the electrophoretically analyzed material, which bound to and was specifically eluted from the various lectin affinity colums. The characteristics of elution of bound material from individual lectin columns indicated secondary hydrophobic interactions between concanavalin A or wheat germ agglutinin and their respective lectin receptor molecules.     

Different effects of lectins on the ligand binding of the NMDA receptors and sigma sites in rat brain hippocampus synaptic membranes

The effects of the lectins concanavalin A, WGA, ricin, abrin, and the mistletoe lectins from Viscum album MLI, MLII, and MLIII on the binding of ligands of the NMDA and sigma receptors in rat hippocampus synaptic plasma membranes were investigated. Binding of [³H]MK-801, [³H]glutamate, [³H]5,7-DCKA, and [³H]glycine to the membranes was decreased by 40-60% after addition of galactose-specific lectins (mistletoe lectins MLI, MLII, ricin, abrin) at concentrations of 0.01 mg/ml, but was not affected by the glucose- and mannose-specific lectin Con A, an acetylglucosamine-specific lectin WGA, or an acetylgalactosamine-specific lectin MLIII. The binding of [³H]SKF 10047 was decreased only in the presence of MLIII and did not change after addition of the other lectins. It is suggested that lectin-sensitive ligand binding sites of sigma- and NMDA receptors are located separately, and that the carbohydrate side chains of the sigma receptor do not participate in the modulation of the NMDA-receptor.     

Glycoconjugates of the human sperm surface: Distribution and alterations that accompany capacitation in vitro

We have studied changes in the binding of fluoresceinated lectins to human sperm during in vitro capacitation. We first determined the surface labeling pattern of viable sperm obtained by the swim-up procedure. Sperm were labeled with 100 μg/ml FITC-conjugated lectin at 4°C for 30 min. We simultaneously used Hoechst stain 33258 as a supravital stain to help differentiate surface from intracellular lectin labeling. Of 14 lectins studied, six (phytohemagglutinin-E, concanavalin A, Ricinus communis agglutinin-I, and the lectins of wheat germ, Lens culinaris, and Pisum sativum) bound to the entire surface of sperm, sometimes with minor local heterogeneity. Three lectins (from peanut, Maclura pomifera, and soybean) usually bound in a punctate manner, with more label on the tail than on the head. Five lectins (Ulex europaeus, Dolichos biflorus, Helix pomatia, and Vicia villosa lectins, and lectin II of Griffonia simplicifolia) bound very poorly or not at all to the sperm surface. Sperm were also inspected for changes in surface lectin binding patterns after 0, 5, and 23 hr of incubation in a capacitating medium. Two lectins showed reproducible changes. The labeling by Maclura pomifera agglutinin decreased by 5 hr in eight of ten experiments, and among sperm labeled with concanavalin A, the incidence of sperm with a highly fluorescent anterior margin of the sperm head increased by about 3.5-fold between 0 and 5 hr. The labeling pattern of the other lectins did not change.     

Correlations between the binding of neoglycoproteins,bovine serum albumin (BSA) and lectins in 10 to 13-day-old mouse embryos

Summary In the present work we compared the appearance of carbohydrate binding sites for mannose, maltose, sialic acid and N-acetyl-glucosamine in the 11 to 13-day-old mouse embryo with the appearance of BSA and lectin binding sites. The carbohydrate-binding sites were localized with FITC-coupled neoglycoproteins, synthesized by chemical glycosylation of bovine serum albumin (BSA). These localizations were compared with binding of the FITC-labelled unglycosylated BSA. Furthermore the localizations of neoglycoprotein and BSA binding sites were correlated with binding of the FITC-labelled lectins WGA, RCA I and Con A. Initial appearance of neoglycoprotein binding sites occurred in the lens capsule of the 13 day old mouse embryo. Binding sites for the unglycosylated BSA appeared earlier, i.e. already in the 12-day-old embryo, in the basement membranes of the choroid plexus and the lung bud and lectin binding sites were seen in these structures in the 11-day-old embryo. The staining of the basement membrane and the lens capsule for BSA binding sites in the 12-and 13-day-old embryos correspond to WGA binding to these membranes. From these results we concluded that 1) specific carbohydrates which are probably involved in embryonic development appear much earlier in the embryo than the endogenous lectins which are able to react with these carbohydrates and 2) BSA is a protein which like WGA probably binds N-acetylglucosamine or sialic acid moieties.     

FITC-labeled lectins and calcofluor white ST as probes for the investigation of the molecular architecture of cell surfaces. Studies on conjugatophycean species

Summary In a screening program with 7 FITC-labeled lectins as probes, ConA receptors were identified in all of the 28 members of theConjugatophyceae, being under investigation. In nearly all of them RCA₁₂₀ receptors, too, are expressed. In 3 species only, PNA receptors, and in 2 species UEA receptors have been detected. No binding of DBA, SBA, and WGA was observed. The receptors for ConA, RCA₁₂₀, and UEA were shown to be associated with different molecules. Each lectin exhibits a unique and specific binding pattern, both chemically, as well as with regard to the topographic distribution on cell surfaces. While ConA receptors predominantly are associated with constituents of the cell wall, RCA₁₂₀ receptors mostly form part of the surrounding mucilage; the same holds for UEA receptors. Besides a variability of topographic distribution and species-to-species variation, a cell-to-cell variation exists in many species, suggesting that the expression of a lectin receptor is due to the developmental state of the cell and/or depends on external stimuli. In conclusion, we may point out, that FITC-labeled lectins turned out to be extremely useful probes for the investigation of the molecular architecture of cell walls. Calcofluor white ST binding to fibrillar polysaccharides (most probably cellulose) was shown to be inhibited by external incrustations of the cell wall. One species does not show any reaction with calcofluor white ST at all.     

Detection of hemicelluloses specific to the cell wall of tracheary elements and phloem cells by fluorescein-conjugated lectins

Summary Binding of fluorescein-conjugated wheat-germ agglutinin (F-WGA) and some other lectins to tissues from various plants were examined by epifluorescence microscopy. F-WGA bound specifically to the walls of tracheary elements (TEs) and phloem cells of pea roots. The binding sites in TEs were localized only in the secondary thickening and became evident at very early stages of differentiation. Fluorescein-conjugated derivatives ofSolanum tuberosum lectin,Lycopersicon esculentum lectin, andDatura stramonium lectin, which bind N-acetylglucosamine residues as WGA, also bound to the secondary thickening of TEs of pea roots. The binding sites for F-WGA were not removed by extraction with hot EDTA and proteinase K, but removed by extraction with an alkali solution. The alkali-extracted binding sites from the roots were precipitated together with hemicelluloses by 80% ethanol. These results indicate that the binding sites are not present on pectins, proteins, or cellulose, but hemicelluloses. Localized distribution of the binding sites for F-WGA in TEs was found also in a variety of angiosperm plants.Abbreviations BSL-II Bandeiraea simplicifolia lectin II - DSL Datura stramonium lectin - F fluorescein-conjugated - LEL Lycopersicon esculentum lectin - MT microtubule - STL Solanum tuberosum lectin - TE tracheary element - WGA wheat-germ agglutinin     

The immuno-histochemical localization of lectin in pea seeds (Pisum sativum L.)

The lectin from the garden pea (Pisum sativum L.) has been localized at the ultrastructural level by the unlabeled peroxidase-antiperoxidase procedure of L.A. Sternberger et al. (1970, J. Histochem. Cytochem 18, 315–333) in 24 h imbibed seeds. Upon examination by light microscopy and transmission electron microscopy, the lectin was only found in the protein bodies of cotyledons and embryo axis. Cell walls as well as membraneous fractions were completely devoid of lectin. These results are discussed in relation to the possible physiological function of seed lectins.Abbreviations PBS phosphate-buffered saline - TBS Tris-buffered saline - PAP-complex horseradish peroxidase-antihorseradish peroxidase soluble complex - NGS normal goat serum - TBS^* Tris-buffered saline containing 0.5 M NaCl, pH 7.6     

Postnatal development of lectin binding sites in the rat ventral prostate

Summary Five Fluorescein-isothiocyanate (FITC)-labelled lectins were used to study the postnatal development of carbohydrate constituents in the rat ventral prostate: Concanavalin A (Con A), wheat germ agglutinin (WGA), peanut agglutinin (PNA),Dolichos biflorus agglutinin (DBA) andRicinus communis agglutinin I (RCA-I) With all the lectins, tested, except RCA-I, specific binding sites could be shown for every stage of differentiation in the glandular epithelium. Binding sites for Con A, WGA, PNA and DBA were found from day 10 to 13 post partum onwards. Each lectin showed a characteristic localization. Binding sites for the lectins used changed to different extents during the following two weeks. After the 24th day post partum no further changes in the lectin binding pattern could be found. The development of the lectin binding properties showed that the changes in carbohydrate-containing constituents of the prostate correlate with the beginning of prostatic secretion and to prostatic epithelial differentiation. In the periacinar stroma the development of the lectin binding pattern was similar to that in the glandular epithelium. The changes of stromal binding sites for Con A and WGA during epithelial differentiation may reflect the changes of epithelial-stromal interactions in the prostate.     

Fluorescein Isothiocyanate-Labeled Lectin Analysis of the Surface of the Nitrogen-Fixing Bacterium Azospirillum brasilense by Flow Cytometry

The cell surface of Azospirillum brasilense was probed by using fluorescein isothiocyanate (FITC)-labeled lectins, with binding determined by fluorescence-activated flow cytometry. Cells from nitrogen-fixing or ammonium-assimilating cultures reacted similarly to FITC-labeled lectins, with lectin binding in the following order: Griffonia simplicifolia II agglutinin > Griffonia simplicifolia I agglutinin > Triticum vulgaris agglutinin > Glycine max agglutinin > Canavalia ensiformis agglutinin > Limax flavus agglutinin > Lotus tetragonolobus agglutinin. The fluorescence intensity of cells labeled with FITC-labeled G. simplicifolia I, C. ensiformis, T. vulgaris, and G. max agglutinins was influenced by lectin concentration. Flow cytometry measurements of lectin binding to cells was consistent with measurements of agglutination resulting from lectin-cell interaction. Capsules surrounding nitrogen-fixing and ammonium-assimilating cells were readily demonstrated by light and transmission electron microscopies.     

Purification and characterization of two major lectins fromVigna mungo (blackgram)

Blackgram (Vigna mungo L. Hepper)seeds contain two galactose-specific lectins, BGL-I and BGL-II. BGL-I was partially purified into two monomeric lectins which were designated as BGL-I-1 (94 kDa) and BGL-I-2 (89 kDa). BGL-II is a monomeric lectin of 83 kDA. The purified lectins were associated with galactosidase activities. BGL-I-1 and BGL-II were copurified with α-galactosidase activity while BGL-I-2 was largely associated with β-galactosidase activity. These lectins agglutinate trypsin treated rabbit erythrocytes, but not the human erythrocytes of A, B or O groups. They were stable between pH 3·5 and 7·5 for their agglutination. The lectins did not show any metalion requirement. They were inactivated at 50°C. The lectin activity was inhibited by D-galactose (0·1 mM). The Scatchard plots of galactose binding to these lectins are nonlinear and biphasic curves indicative of multiple binding sites. The data show that the monomeric lectins have both lectin and galactosidase activities suggestive of a bifunctional protein.     

Lectin binding sites during Drosophila embryogenesis

The spectrum of lectin binding sites as it emerges during embryonic development of Drosophila was analysed by means of fluorescein-labelled lectins. As development and morphogenesis proceed, the reaction pattern becomes more and more complex. Mannose/glucose-, mannose-, N-acetylglucosamine- and poly-N-ace-tylglucosamine-specific lectins bind ubiquitously. Nuclear envelopes only have binding sites for wheat germ agglutinin. N-acetylgalactosamine-binding lectins are specific for ectodermal derivatives. Ga-3-N-acetylgalac-tosamine-binding lectins are highly selective markers for neural structures, haemocytes and Garland cells. It is also shown that Drosophila laminin is differentially glycosylated. The possible implications of differential and germ layer-specific glycosylation are discussed.Dedicated to the memory of Jan Callaerts     

Localization of surfactant protein A (SP-A) in alveolar macrophage subpopulations of normal and fibrotic rat lung

The colocalization of surfactant protein A (SP-A) and the alveolar macrophage markers ED1 and RM-1, as well as various lectins of the N-acetyl-galactosamine group [Maclura pomifera lectin (MPA), Dolichos biflorus lectin (DBA), soybean agglutinin (SBA)] and of the mannose group [Canavalia ensiformis lectin (ConA), Galanthus nivalis lectin (GNA)] was studied in normal and fibrotic rat lung tissues. In normal tissue, SP-A was located preferentially in the alveolar macrophage subpopulation lacking specific binding sites for lectins of the N-acetylgalactosamine group (DBA and SBA), although 50% of MPA-binding macrophages contained SP-A. The ED1-positive cells were SP-A-negative, whereas SP-A uptake could be detected among the RM-1 immunoreactive as well as the ConA and GNA binding macrophages. In fibrotic lung tissue, however, a small number of .DBA and SBA binding macrophages contained SP-A and the percentage of GNA and ConA binding alveolar macrophages exhibiting SP-A immunoreactivity was reduced. Additionally, the number of ED1⁺/SP-A⁺ macrophages was found to be increased. Immunoelectron microscopy revealed accumulation of SP-A in the extracellular space. The differing SP-A content in different alveolar macrophage subpopulations suggests a more complex mechanism of uptake and degradation of surfactant proteins in normal and pathological conditions, which cannot simply be explained by the glycoconjugate pattern on the surface of alveolar macrophages.     

FRACTIONATION OF GLYCOPROTEINS ASSOCIATED TO ADULT RAT BRAIN MYELIN FRACTIONS

Abstract— The chloroform-methanol insoluble residue of adult rat brain myelin fractions (My-CMI) contains only 20% of protein but all myelin-associated glycoproteins (Z anetta et al ., 1977a). After solubilization in sodium dodecyl sulphate, these glycoproteins were separated by sequential affinity chromatography on 4 immobilized lectins. Ten fractions (9 of which contained only glycoproteins) were obtained. Glycoproteins added up to at least 25% of My-CMI proteins. Many minor glycoproteins were detected in the different fractions. However most of them appeared not to be intrinsic to myelin. On the contrary a major glycoprotein electrophoretic band, component A, appeared to be intrinsic to myelin although its presence also on oligodendrocyte plasma membrane cannot be excluded. Component A was tentatively identified with the'major myelin associated glycoprotein'described by QUARLES (1972, 1973 a, b ). It accounted for less than 0.4% of proteins and 8% of glycoproteins of myelin fractions and consisted of at least two'glycopolypeptides'which, both, bind to concanavalin A and to the Ulex europeus lectin. The other major glycoprotein, component B, did not bind to any of the lectins used and, thus, must have N -acetyl neuraminic acid as only terminal sugar. The separation of myelin-associated glycoproteins according to their affinity for lectins allowed a tentative identification of the lectin binding sites of myelin sheath.     

Interactions of galactose-binding lectins with plant protoplasts

Summary Protoplasts isolated from cell suspension cultures of carrot (Daucus carota L.) and leaves of tobacco (Nicotiana tabacum L.) were treated with three lectins specific for galactosyl residues. After incubation with RCA I (Ricinus communis agglutinin, molecular weight 120,000) conjugated to ferritin or fluorescein, freshly isolated protoplasts displayed heavy labeling of their surfaces. Moreover, they agglutinated rapidly when exposed to low concentrations of RCA I. In parallel studies, PNA (peanut agglutinin) also bound extensively to the protoplast plasma membranes whileBandeiraea simplicifolia lectin I attached relatively weakly. When protoplasts were cultured for two days and then incubated with conjugates of RCA I and PNA, additional binding sites were revealed on the regenerating walls.The results indicate that galactosyl residues are distributed densely over the surface of plant protoplasts. They also allow inferences to be made regarding the positions and linkages of the galactose groups being recognized by the lectins. Moreover, they open up the question whether the galactosyl moieties detected in the wall derive from those labeled on the plasma membrane. To conclude, we make comparisons with binding by concanavalin A, and predict that galactose-recognizing lectins will join and in certain respects prove superior to concanavalin A as probes of the plant cell surface.     

Localization of the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes

Freeze-etch electron microscopy has been utilized to localize the binding sites for the Ricinus communis, Agaricus bisporus and wheat germ lectins on human erythrocyte membranes and to determine the relation of these different glycoprotein receptors to the intramembranous particles. A. bisporus lectin, which could be visualized directly on the surface of erythrocyte membranes, and ferritin conjugates of wheat germ agglutinin showed a distribution that correlates exactly with the intramembranous particles at all lectin concentrations tested. The binding sites for both of these lectins are located on the major sialoglycoprotein of the membrane. The R. communis agglutinin-ferritin conjugate which binds to receptors on membrane glycoproteins that are distinct from the major sialoglycoprotein showed a close correlation with the intramembranous particles at low lectin concentrations and a poor correlation at high lectin concentrations. High concentrations resulted in virtually complete coating of the surface of trypsinized ghosts which displayed marked aggregation of the intramembranous particles. We conclude that the intramembranous particles of erythrocyte membranes contain at least two glycoproteins and that some membrane lectin receptors are not associated with the intramembranous particles.     

Lectin-binding properties of hamster egg zona pellucida and plasma membrane during maturation and preimplantation development

The structure and organization of the zona pellucida and plasma membrane of the hamster egg at various stages of maturation and development were examined using lectin-mediated agglutination and the binding of fluorescent-labeled lectins. Ricinus communis I and Dolichos biflorus lectins specifically agglutinated the zona pellucida of both unfertilized and fertilized eggs, while wheat germ agglutinin (WGA) only agglutinated eggs which had been pretreated with protease. Six other lectins failed to agglutinate even eggs pretreated with protease. A comparison of the lectin-binding sites on the zona pellucida of eggs in various stages of maturation and development revealed that the intensity of binding and distribution of fluorescent-labeled lectins remain unchanged. Zona-free eggs were agglutinated by every lectin tested except those recognizing -fucose-like residues. Fertilized zona-free eggs were slightly more agglutinable by concanavalin A (ConA), Lens culinaris and WGA than unfertilized eggs. When the surfaces of zona-free eggs were examined with fluorescent ConA, Ricinus communis I and WGA, maximal binding was seen when eggs reached full maturity and binding decreased during the later stages of preimplantation development.     

An immunofluorescence study on lectin binding sites in gametes of Ectocarpus siliculosus (Ectocarpales, Phaeophyceae)

The distribution of binding sites for the lectins WGA, DSA. RCA I, PNA, AAA, MAA. SNA, GNA. and Con A in gametes of both sexes of the brown alga, Ectocarpus siliculosus (Dillw.) Lyngbye, was investigated by fluorescence microscopy. Digoxigenin-conjugated lectins and an FITC-anti-digoxigenin antibody were used as a high sensitivity detection system. Organelles and other distinct cellular domains could be distinguished by their binding specificities. Glycoconjugates associated with one flagellum were found to be associated with the axoneme by lectin binding to isolated flagellar apparatuses. In addition, changes in the distribution of carbohydrate epitopes during the attachment of gametes to the substratum were revealed by differential lectin binding.