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PubMed1987

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 micrograms/ml FITC-conjugated lectin at 4 degrees 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.

Fluorescein-5-isothiocyanate↗
PubMed1998

Detection of lectins using ligand blotting and polyacrylamide-type glycoconjugate probes.

A sensitive and convenient method for detection of the carbohydrate-binding activity of lectins was established using the combination of blotting of lectins on polyvinylidene difluoride membranes, carbohydrate-conjugated biotinylated polyacrylamide-type probes (carbohydrate-bp probes), horseradish peroxidase-streptavidin, and detection by enhanced chemiluminescence of the enzyme reaction. This method was tested for detection of four plant lectins blotted on the membrane: concanavalin A was detectable down to 100 ng by mannose-bp probe, Ricinus communis agglutinin 120 to as low as 5 ng by N-acetyllactosamine-bp probe, soybean agglutinin to 1 microgram by beta-N-acetyl-D-galactosamine-bp probe, and wheat germ agglutinin to 5 ng by beta-N-acetyl-D-glucosamine-bp probe. All four lectins were detectable on an electroblotted membrane after SDS-polyacrylamide gel electrophoresis. This method was used to detect recombinant human galectin-3 in Escherichia coli cell lysates and mannan-binding protein in human serum. These results indicate that this method is widely applicable to convenient detection and characterization of lectins in crude samples.

Acrylic Resins↗
PubMed1994

Chemoenzymic preparation of a glycoconjugate polymer having a sialyloligosaccharide: Neu5Ac alpha (2-->3)Gal beta (1-->4)GlcNAc.

Water-soluble polyacrylamide having 3'-sialyl N-acetyl-lactosamine [Neu5Ac alpha (2-->3)Gal beta (1-->4)GlcNAc] was enzymatically prepared by stepwise sugar-elongation on a water-soluble GlcNAc-bearing polyacrylamide. It was demonstrated that the flexible GlcNAc branches of the polymer chains allow quantitative galactosylation with bovine galactosyl transferase and partial sialylation by Trypanosoma cruzi trans-sialidase. Unsialylated N-acetyl-lactosamine side chains can be removed with beta-D-galactosidase and N-acetyl-beta-D-glucosaminidase to afford the targeted polymer containing 3'-sialyl N-acetyl-lactosamine.

Acetylgalactosamine↗
PubMed1998

Specific glycoconjugates are present at the oolemma of the fertilization site in the egg of Discoglossus pictus (Anurans) and bind spermatozoa in an in vitro assay.

In the egg of the anuran Discoglossus pictus, the site of fertilization is restricted to the central portion of an animal hemisphere indentation (the dimple). Previous studies showed that the acrosome reaction of D. pictus sperm is triggered in the jelly, and yet sperm arrive at the dimple surface with the plasma membrane at an early stage of vesiculation. Reactivity of the dimple surface with specific lectins suggests that fucose might be utilized as a marker of glycoproteins located at the dimple surface. In this paper, proteins of the egg surface were labeled with the membrane impermeable sulfo-NHS-biotin. Four main bands of 200, 230, 260, and 270 kDa labeled only at the dimple surface, although they were detected in the cortex of the whole egg. The 270-kDa band reacted with Galanthus nivalis agglutinin only in the cortex of the dimple, suggesting that this band is differently glycosylated according to its localization. The alpha-l-fucose-specific lectin Ulex europaeus agglutinin I was utilized both in lectin blotting and in affinity chromatography and cross-reacted with the 200- and 270/260-kDa bands. Furthermore, two polypeptides were obtained by exposure of intact eggs to lysylendoproteinase C. They were also reactive to Ulex europaeus agglutinin I. The 200- and 270/260-kDa bands were eluted from the acrylamide gels and adsorbed to polystyrene beads. An assay for sperm binding to 200-kDa glycoprotein-bound beads was developed. Sperm stuck to the beads before but not after Ca-ionophore treatment. When the beads were coated with the 270/260-kDa glycoproteins, binding occurred after ionophore treatment. In these assays, the 200- and 270/260-kDa glycoproteins competitively inhibited sperm binding to the beads coated with the corresponding glycoprotein. These results indicate that the assayed glycoproteins, located either in the glycocalyx or in the plasma membrane of the fertilization site, are involved in sperm binding.

Animals↗
PubMed1994

Glycoconjugates of the normal human colorectum: a lectin histochemical study.

Previous studies of the normal human colorectum by lectin histochemistry have used a mixture of tissues, including those derived from colons harbouring neoplasia and inflammatory bowel diseases. In the current investigation, tissues from patients without either of these conditions have been examined with a wide panel of lectins, encompassing specificities directed against both N- and O-linked sequences, using an avidin peroxidase revealing system and evaluated with a semiquantitative scoring method. The results of binding of these lectins have been compared with those seen in the resection margins of (at least 5 cm away from) colorectal carcinomas. Consistent regional variations were noted between right- and left-sided colonic tissues, with more diverse glycan structures and a greater sialyl content in the distal colon. There was evidence of graduation of formation of oligosaccharide chains in developing crypts, possibly related to the maturation and expression of glycosyl transferases responsible for the incorporation of mannose residues of N-linked oligosaccharides and of N-acetylgalactosamine and N-acetylglucosamine. Comparison with previous reports has revealed some variations, possibly related to tissue fixation and processing and to lectin concentrations employed, which raises the question of standardization of methodologies in lectin histochemical investigations.

Colon↗
PubMed1994

Distribution patterns in glycoconjugate expression during the development of the rat palate.

The distribution of complex carbohydrate structures during the embryonic development of the rat palate was analysed by examining lectin-binding patterns in serial paraffin and cryostat sections. With few exceptions, the binding patterns showed a general increase in lectin receptors in the more developed stages of palatogenesis. High mannose oligosaccharides were especially amplified during development. Terminal fucose molecules were not expressed. In contrast, terminal sialic acid molecules were ubiquitously distributed in epithelial and mesenchymal tissues. Non-sialylated terminal N-acetylglucosamine was specifically restricted to evolving bone matrix. Before palatal fusion, quantitative but not qualitative differences were detected between oral, nasal, and medial-edge epithelial surfaces. The only exception was LCA, which specifically marked epithelial cells at the tip of palatal shelves. A very selective affinity for Jacalin was demonstrated in the oral epithelium of the palate after day 16, suggesting the presence of sialylated terminal galactose-(beta-1,3)-N-acetylgalactosamine. PNA specifically marked the basal lamina of the oral side of palatal processes. The binding patterns of DBA, GSL IA, SBA, and VVA indicated that the epithelium of the tongue is characterized by terminal alpha- and beta-galactose residues, whereas palatine cells possess only molecules with beta-anomery. During palatogenesis, glycosaminoglycans patterns were significantly modified. Our data suggest that alteration of complex carbohydrate structures may play a central role in modulating cell-cell and cell-matrix interactions. The significance of these findings, however, remains to be elucidated.

Acetylglucosamine↗
PubMed1993

Histochemical analysis of rat testicular glycoconjugates. 3. Non-reducing terminal residues in seminiferous tubules.

Lectins of Helix pomatia (HPA), Glycine max (SBA), Vicia villosa (VVA), Dolichos biflorus (DBA), Ulex europaeus (UEA-1), Tetragonolobus purpureus (LTA), Griffonia simplicifolia (BSA-1B4), Maclura pomifera (MPA), Sambucus nigra (SNA) and Maackia amurensis (MAA) were used to explore the distribution of saccharides characteristic of non-reducing termini of O- and N-linked glycoprotein glycans in the seminiferous tubules of rat testis. Sialyl residues (both alpha 2,3- and alpha 2,6-linked, as shown by MAA and SNA respectively) and alpha-L-fucosyl residues (shown by UEA-1 and LTA) were expressed on spermatogonia, spermatocytes and spermatozoa, but not on spermatids. In contrast, 2-deoxy-2-acetamido-alpha-D-galactosyl termini were abundant on spermatozoa, but not on any of their precursors (as shown by HPA, SBA and VVA). All occurred on both O- and N-linked glycans. Sertoli cells expressed small amounts of fucose and alpha 2,3-linked sialic acid, and abundant alpha 2,6 sialyl residues, largely on N-glycans. alpha-Galactosyl residues were readily detected on the tubular basement membrane, but not elsewhere.

Animals↗
PubMed1995

Characterization of glycoconjugate expression during development of Meckel's cartilage in the rat.

The staining patterns of 24 biotinylated lectins were analyzed in serial sections of the mandible of 13- to 21-day-old rat embryos by means of the avidin-biotin-peroxidase method. A ubiquitous distribution of binding sites was demonstrated after incubation with Con A (Canavalia ensiformis), DSL (Datura stramonium; except bone matrix), and WGA (Triticum vulgare). ECL (Erythrina cristagalli), GSL I (Griffonia simplicifolia), SJA (Saphora japonica), VVL (Vicia villosa), DBA (Dolichus biflorus), UEA I (Ulex europeus), and LTA (Lotus tetragonobolus) were constantly negative. In early stages of development, GSL II (Griffonia simplicifolia II) was a selective marker of prechondral blastema. In contrast, PNA (Arachis hypogaea) did not stain condensing mesenchyme. During chondrogenesis of Meckels's cartilage a general decrease of lectin binding was observed. Mature cartilage matrix was constantly negative. Chondrocytes were marked by the lectins PSA (Pisum sativum), WGA, PHA-E, and PHA-L (Phaseolus vulgaris E and L). A strong GSL II binding was restricted to the mesial-superior region of the perichondrium. In later stages, several lectins revealed significant differences between preskeletal ("central") areas and the remaining ("peripheral") mesenchyme. A clear binding reaction was noted in central regions by applying LEA (Lycopersicon esculentum) and STL (Solanum tuberosum), while the peripheral tissue was only faintly stained. Developing bone was specifically marked by succinylated WGA (sWGA). The lectins LCA (Lens culinaris) and RCA (Ricinus communis) bound to fibers and extracellular matrix of the connective tissue. Jacalin (Artocarpus integrifolia) and SBA (Glycine max) binding sites were found in macrophages. Affinity of VAA (Viscum album) increased parallel with maturation of endothelial cells. Specific lectin-binding patterns revealed no correlation with the distribution of glycosaminoglycans. The results demonstrate a general reduction of oligosaccharide structures during development of Meckel's cartilage. From our observations we conclude that intralaminar glucose and/or mannose sequences as well as terminal sialic acid molecules are ubiquitously distributed, while terminal alpha-fucose was constantly negative. Lectin-binding patterns of macrophages may reflect the presence of specifically linked terminal galactose. Our findings indicate that oligosaccharides terminating in N-acetylglucosamine are bone-specific. The significance of the restricted staining of the perichondrium by GSL II remains to be elucidated.

Animals↗
PubMed1992

Immunohistochemical demonstration of glycoconjugates bearing the type 2 chain-backbone structure in human fetal, normal and neoplastic gastrointestinal tract.

Immunohistochemical distributions of carbohydrate antigens based on the type 2 chain in normal as well as fetal and neoplastic tissues of human gastrointestinal tract were investigated with a monoclonal antibody (MAb) H11 (specific for type 2 chain) alone and in combination with the two MAbs MSG15 (for alpha 2----6 sialylated type 2 chain) and IB9 (for the alpha 2----6 sialylated type 2 chain and glycoproteins having NeuAc alpha 2----6Gal-NAc), and 188C1 (for short- and long-chain Lex antigens) and FH2 (for the long-chain Lex antigen). In the pyloric mucosa of secretors, the type 2 chain is oncodevelopmentally expressed, but in non-secretors it is detected in surface mucous cells of normal gastric mucosa. The alpha 2----6 sialylation, which is confined to endocrine cells of normal pyloric mucosa, occurs in fetal and carcinoma tissues. Irrespective of the secretor status, the short- and the long-chain Lex antigens can be detected in mature and immature glandular mucous cells of normal gastric mucosa, respectively; both antigens are also expressed in fetal and carcinoma tissues. In the colon, the type 2 chain and its alpha 2----6 sialylated counterpart are expressed in an oncodevelopmental manner. The short- and the long-chain Lex antigens are significantly enhanced in colonic carcinoma. The glycoproteins with NeuAc alpha 2----6GalNAc residues appear in gastric and colonic carcinoma as well as intestinalized gastric mucosa and transitional mucosa. Thus, some of these antigens were distinctively expressed in certain epithelial cells lining the normal gastrointestinal tract depending on maturation and patients' secretor status, and some were oncodevelopmental or carcinoma-associated antigens of the human gastrointestinal tract.

Antibodies, Monoclonal↗
PubMed1993

Glycoconjugates with Neu5Ac(alpha 2,6)Gal(beta 1,4)GlcNAc sequences: a selective lectin-histochemical property of Kurloff cells in guinea pig thymus.

The Kurloff cell (KC), a natural killer lymphocyte, contains a large (10-microns diameter) periodic acid-Schiff (PAS)-positive lysosome-like inclusion body called the Kurloff body (KB), which exhibits strong acid phosphatase activity. The presence of Sambucus nigra agglutinin (SNA)-reactive Neu5Ac(alpha 2,6)-D-Gal/Gal-NAc(beta 1,4)GlcNAc oligosaccharide sequences and the absence of the corresponding Neu5Ac(alpha 2,3) Maackia amurensis agglutinin (MAA)-reactive sequence in the major 35-kDa N-glycosylproteins of the complex or hybrid type extracted from purified KC were established by Western-lectin-blotting of cytosolic extracts from purified KC. Moreover, these SNA-reactive sequences, or at least part of them, were shown to be borne by sialidase-sensitive KC acid isophosphatases. Thymic sections rich in KC, from estrogenized guinea pigs were examined by affino-histochemistry with these sialic acid-reactive lectins. The SNA-reactivity of thymic sections was quasi-exclusively confined to KC clusters, whereas the whole thymic section was negative for MAA. KC were not SNA-reactive following preincubation and incubation with 200 mM lactose. When submitted to enzymatic or mild chemical desialylation processes, the SNA-reactivity of the KC clusters was enhanced. The SNA-reactivity of KC clusters was completely abolished following prolonged chemical desialylation, whereas the PAS-positivity of KB remained unchanged. Even after a prolonged sialidase treatment, this SNA-reactivity was only reduced. Moreover, after both these desialylation processes, KC developed a heavier Ricinus communis agglutinin-reactivity, thus confirming the presence of penultimate Gal residues in their abundant SNA-reactive oligosaccharide sequences Neu5Ac(alpha 2,6)Gal(beta 1,4)GlcNAc. Such a selective lectin histochemical property provides a marker for detecting KC.

Animals↗
PubMed1987

Light microscopic characterization of glycoconjugates in secretory cells of the carp (Cyprinus carpio) gill epithelium.

Secretory products of granular and mucous cells in the gill epithelium of the carp, Cyprinus carpio, were distinguished by their cytochemical reactions with peroxidase-labelled lectins and with the galactose oxidase (GO)-Schiff reagents. Secretory products of granular cells reacted with lectins from Triticum vulgaris (WGA), Arachis hypogaea (PNA), Dolichos biflorus (DBA), Glycine max (SAB), and Lotus tetragonolobus (LTA). They also reacted with GO-Schiff reagents. After sialic acid cleavage with HCl, new binding sites for DBA and SBA appeared, suggesting the terminal sequence sialic acid-N-acetylgalactosamine (SA-GalNAc) for the secretion of this cell type. In mucous cells, binding sites for WGA, DBA, and SBA and, after acid hydrolysis, binding sites for PNA and a positive GO-Schiff reaction were detected. The terminal trisaccharide sialic acid-galactose (beta 1-3)-N-acetylgalactosamine (SA-Gal-GalNAc) is proposed for the secretion of mucous cells. These cytochemical differences are discussed in light of the involvement of both cell types in fish mucus elaboration.

Animals↗