Helen Tortorella
Universidade Federal do Rio Grande do Sul
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Featured researches published by Helen Tortorella.
Theriogenology | 2002
V.S.N La Falci; Helen Tortorella; J.L. Rodrigues; Adriano Brandelli
The present study describes the investigation of seasonal changes in seminal plasma proteins of Saanen goats under natural conditions in south Brazil. Proteins were isolated by liquid chromatography on heparin Sepharose CL-6B column and characterized by polyacrylamide gel electrophoresis (PAGE). Important differences were observed in the pattern of heparin-affinity proteins (HAPs), such as a band of 178 kDa unique to the breeding season; a decrease in 119 kDa proteins; and an increase in proteins ranging from 73 to 104 kDa. HAP caused deterioration of sperm motility and acrosome breakage in media containing and not containing skimmed milk; the effect was most remarkable with the proteins from the nonbreeding season. Furthermore, HAP presented phospholipase A2 (PLA2) activity, which was 4.4-fold higher in nonbreeding season than in breeding season. Binding sites for HAP were identified in the sperm surface, particularly at the middle piece of the spermatozoa. These results indicate that proteins from goat seminal plasma are under seasonal control and associated with sperm function during breeding and nonbreeding seasons.
Glycoconjugate Journal | 1998
Carlos H.G.L. Lopes; María N. Mazzini; Helen Tortorella; R.A Konrath; Adriano Brandelli
Affinity chromatography on Concanavalin-A Sepharose, followed by gel filtration and hydrophobic interaction chromatography, permits the isolation of low molecular weight N-glycosidically linked oligomannosidic glycopeptides (MGp) from the autoproteolysis products of human seminal plasma. The monosaccharide composition of MGp showed only mannose, N-acetylglucosamine and a small amount of galactose. Structural studies were carried out by methylation analysis and chromium trioxide oxidation, and results were consistent with the structures accepted for high-mannose N-glycans. MGp was capable of inhibiting the sperm acrosomal exocytosis mediated by sperm-surface receptors. These data suggest that MGp act as a “decapacitation” factor preventing premature sperm exocytosis.
American Journal of Reproductive Immunology | 1983
Helen Tortorella; M. Josefina; Scacciati De Cerezo; María N. Mazzini; Alberto S. Cerezo
ABSTRACT: Immunodiffusion, immunoelectrophoresis, SDS‐polyacrylamide gel electrophoresis, polyacrylamide gel electrophoresis, ultracentrifugation analysis, and gel permeation chromatography in chaotropic and detergent mediums showed that the human seminal plasma obtained and stored in the usual way is mainly composed by heterodispersed glycoproteins of low molecular weight.
Brazilian Journal of Medical and Biological Research | 1997
Helen Tortorella; Renato Augusto Konrath; María N. Mazzini; Adriano Brandelli
Sperm-surface glycopeptides were obtained from intact sperm membranes after proteolytic release by different enzymatic treatments such as autoproteolysis, trypsin, papain and pronase. Glycopeptides were isolated, their properties and composition were examined, and their monosaccharide and amino acid constituents were characterized. The monosaccharides identified were fucose, mannose, galactose, N-acetylglucosamine, and N-acetylgalactosamine, which form part of more than one type of oligosaccharide units. Autoproteolytic treatment mainly provided O-glycosidic type oligosaccharides, while a mixture of O- and N-glycosidic oligosaccharides was obtained in variable proportions when treated with trypsin, papain or pronase. The highest degree of peptide cleavage was obtained with pronase. Despite the higher yields reached with trypsin, these glycopeptides contain the lowest percentage of oligosaccharide chains. Proteolytic treatment provides a simple, rapid procedure for the isolation of glycopeptides from the sperm surface.
Analytical Letters | 1988
Helen Tortorella; María N. Mazzini; Alberto S. Cerezo
Abstract The actual fucose content of a glycoprotein or a polysaccharide can be determined without previous hydrolysis of the samples by extrapolating to zero time the curve obtained by plotting the amount of fucose against time of heating in sulphuric acid solution in the determination. Evidence is presented which indicates that fucose is not degraded by the acid treatment but by reaction with other compounds produced in the acid reaction medium.
Medical Science Research | 1996
Edison Capp; Adriano Brandelli; Heleusa Ione Monego; M. F. Ribeiro; M. S. De Freitas; Regina Pessoa Pureur; Helen Tortorella; Helena von Eye Corleta
Archive | 1996
Helen Tortorella; Regina Pessoa Pureur; Marta Sampaio de Freitas; Heleusa Ione Monego; Helena von Eye Corleta; Adriano Brandelli; Edison Capp; Leoni de Oliveira Dias
Archive | 1996
Helen Tortorella; Vera Sn La Falci; Celito Luiz Diel
Archive | 1996
Alessandro Riffel; Lúcia Brugnara; Helen Tortorella; Eduardo Pandolfi Passos; Adriano Brandelli
Archive | 1996
Carlos H.G.L. Lopes; Celito Luiz Diel; Helen Tortorella