Acta histochemica 108 (2006) 475—479 The Con-A-peroxidase method for tissue localization of glucosyl and mannosyl groups applied to mouse hepatocytes and chicken erythrocytes Alberto S. Moraes, Maria Luiza S. Mello à Department of Cell Biology, Institute of Biology, State University of Campinas (Unicamp), P.O. Box 6019, 13083-863, Campinas, Sa˜o Paulo, Brazil KEYWORDS Chicken erythro- cytes; Concanavalin A; Con-A-peroxidase; Lectin; Mouse hepatocytes; Nuclear glycopro- teins; Nuclear matrix Summary A variation of the Concanavalin A (Con-A)-peroxidase labelling method originally described by Kiernan [Localization of alpha-D-glucosyl and alpha-D-mannosyl groups of mucosubstances with Concanavalin A and horseradish peroxidase. Histochemistry 1975;44:39–45] was applied to unsectioned cell preparations, with an emphasis on the nuclear localization of glycoproteins. Mouse liver imprints and chicken blood smears fixed in acetic acid-ethanol solution were studied. Modifications of the method included using increased Con-A concentration, and a range of pH values for the Con-A solutions. The strongest Con-A labelling of both erythrocytes and hepatocytes was obtained after incubation with Con-A at pH 6.5 and with Con-A concentrations at least two-fold greater than those used for tissue sections. These conditions may alter the Con-A conformation, enabling the lectin molecule to enter the cell nucleus and bind to nuclear glycoproteins, thus allowing their localization and quantification. & 2006 Elsevier GmbH. All rights reserved. Introduction Lectins are proteins that bind to sugar moieties in cell walls or membranes and change the physiology of the cell membrane to cause agglutination, mitosis, and other intracellular biochemical altera- tions (Goldstein et al., 1980). Concanavalin A (Con- A), a protein extracted from the seeds of Canavalia ensiformis (jack bean), is a member of this sugar- binding protein family. Con-A has affinity for a-D- glucosyl and a-D-mannosyl residues (Lis and Sharon, 1973). The conformation of Con-A is pH-dependent. At pH below 5.6, the protein exists as a dimer, while at ARTICLE IN PRESS www.elsevier.de/acthis 0065-1281/$ - see front matter & 2006 Elsevier GmbH. All rights reserved. doi:10.1016/j.acthis.2006.09.001 à Corresponding author. Tel.: +551937886122, fax: +551937886111. E-mail address: mlsmello@unicamp.br (M.L.S. Mello).