PubMed Health⌕ Search

Biomedical subjects

J M de Cerezo

Publications and source records attributed to J M de Cerezo.

7 recordsLinked to original sources
PubMed1996

Fucosylated glycoconjugates of the human spermatozoon. Comparison of the domains of these glycoconjugates with the alpha-fucosyl binding sites, and with lactosaminic glycoconjugates and beta-D-galactosyl binding site domains.

Fucosylated glycoconjugates play an important role in fertilization as the recognition signal of the zona pellucida. In this work, using "critical" concentrations of either, FITC Lotus tetragonolobus lectin or FITC alpha-L-fucosyl-BSA neoglycoprotein as molecular probes, population densities of fucosylated glycoconjugates and of their "complementary" molecules (carrying fucosyl receptors), were found all over the sperm surface with higher population densities in post acrosomal sheath, neck and midpiece. These results were compared with previously reported data on the population densities of lactosaminic compounds and their "complementary" molecules, obtained on same samples of spermatozoa. Statistical data demonstrate that fucosylated glycoconjugates share the same domains with biantennary N-acetyllactosaminic oligosaccharides carrying outer galactose and bisected N-acetylglucosamine residues. These domains highly differ with those of the lactosaminic glycoproteins carrying tri and tetraantennary N-acetyllactosaminic oligosaccharides. These studies also show that the domains of fucosylated glycoconjugates and their "complementary" molecules (carrying fucosyl receptors) locate in different zones of the spermatozoon than those of the compounds carrying beta-galactosyl receptors. Besides, the results suggest structural differences between fucosylated glycoconjugates of the acrosome, equatorial zone and post acrosomal sheath. This may be relevant to the different biological behavior of these compounds and zones, in fertilization.

Amino Sugars↗
PubMed1988

Cytochemical detection of receptors specific for N-linked oligosaccharides of glycoproteins in the membrane of the human spermatozoon and their distribution in the different zones of that membrane.

The horseradish peroxidase (HRP), a glycoprotein rich in mannose and N-acetylglucosamine residues has been used as a ligand to detect receptors for N-glycosidic linked oligosaccharides of glycoproteins in the human spermatozoon. Specific binding of HRP occurred to the membrane and the binding sites were visualized with 3,3'-diaminobenzidine-H2O2 (DAB-H2O2) reagent, and by fluorescence when the FITC-peroxidase was used. This specific binding was suppressed by alpha-D-methyl-mannoside and human chorionic gonadotropin, decreased by follicle stimulating and luteinizing hormones and slightly diminished by N-acetylglucosamine. The distribution of the N-linked oligosaccharide specific receptors for glycoproteins in the different zones of the membrane of the spermatozoon was determined by counting the spermatozoa labeled in those zones. The pattern of the distribution is similar to that found for N-linked oligosaccharides containing glycoproteins of the same membrane. The similarity of these distributions together with the general model for cell-to-cell recognition suggest that the sperm-egg interaction mechanism could consist of dual interactions by double binding receptors.

Cell Membrane↗
PubMed1986

Carbohydrates of the surface of the normal human spermatozoon.

Autoproteolysis of human spermatozoa produces oligopeptides with oligosaccharide chains of the N-glycosidic-linked type that are released from the "surface exposed" parts of glycoproteins. The products eluted in the previous washing of the spermatozoa have the same composition and solubility characteristics as the oligopeptides from the digestion. This suggests that autoproteolysis is a constant process that normally occurs on the spermatozoa membrane. The cytochemical characterization and localization of the N-glycosidic-linked oligosaccharide receptors on the human spermatozoa membrane after digestion, in the presence or absence of seminal plasma, indicates that only part of the oligosaccharides are cleaved. Their distribution on the different zones of the spermatozoon changed as the probability of detecting these receptors in the intermediate segment increased after proteolysis; this indicates that in this zone the receptors are cryptic ones that become exposed by the action of the proteolytic enzymes. In the presence of seminal plasma most receptors on the acrosome are eliminated.

Carbohydrates↗
PubMed1985

Cytochemical characterization and localization of oligomannosidic oligosaccharide receptors on the normal human spermatozoa using fluorescent lectins: comparison of different fixation procedures.

Similar locations of the Con A and wheat germ lectin receptors were obtained by using fluorescent lectins, in nonfixed spermatozoa and in spermatozoa fixed with formaldehyde and methanol, showing that in samples with the same previous treatment, worked out by the same operator, in which enough determinations have been performed to eliminate individual variations, the different procedures of fixation produced similar results. The locatizations obtained with fluorescent lectins confirm previous results, produced with the peroxidase technique, indicating that the lectins interact with oligomannosidic oligosaccharide receptors situated mainly in the equatorial segment of the acrosome and postnuclear cap. They also indicate the presence of similar receptors that were not detected previously on the neck and intermediate segment. The larger size of the lectin-peroxidase-diaminebenzidine reagent compared to that of the fluorescent lectins suggests that the new receptors are semicriptic and were not detected by steric effects in the first case, but were able to interact with lower volume, fluorescent probes. It is suggested that these oligomannosidic chains could be recognition signals for the elimination of incompetent sperm during their passage through the female reproductive track. Also these oligosaccharides and its possible metabolic variations could be involved in the interaction between the acrosome-reacted spermatozoa with the zone pellucida.

Concanavalin A↗
PubMed1982

Immunoserological, immunohistochemical and immunobiological studies on an antigenic glycoprotein isolated from human seminal plasma.

The seminal plasma and a fraction of the spermatozoal membrane solubilised by sarkosyl contain similar antigenic determinants. The glycoprotein isolated from the seminal plasma also contains determinants which are immunologically identical to those of the sarkosyl soluble fraction. Three of these determinants were identified as: two oligosaccharide chains with terminal N-acetyl neuraminic acid and with subterminal alpha-L-fucopyranose and beta-D-galactopyranose residues respectively, and an oligosaccharide chain with beta-D-galactopyranose as non-reducing end-chain. The receptors on the spermatozoa to anti-glycoprotein and anti-seminal plasma antibodies are localized. The specificity of the receptors localised in the neck region depends entirely on the presence of N-acetyl neuraminic acid as end-chain group while the specificity of the receptors to the anti-seminal plasma antibodies in the intermediate segment plus tail and to the anti-glycoprotein antibodies in the post-nuclear cap depends also on the subterminal units. At least two other receptors in the equatorial zone are ended by residues different from the N-acetyl neuraminic acid. One of them, which is also found in the acrosome, does not have specificity for anti-glycoprotein antibodies, while the other, which is not in the acrosome, has anti-glycoprotein antibodies specificity and may have a terminal beta-D-galactopyranose residue.

Antigens↗
PubMedDate not supplied

Immunological response of guinea pigs sensitized with homologous antigens.

The chemical composition of some "immunologically" pure antigens isolated from guinea pig testis and spermatozoa was correlated with their antigenic behavior. Their immunological responses were compared to select the best materials for a further isolation of chemically pure antigens. The glycoprotein extracted from the spermatozoa (T Gly) has the highest immunological potency and seems to be a T and B, depending antigen, able to induce high humoral and cell responses producing germinal cell damage, testicular lesions, and aspermatogenesis.

Animals↗