Histochemical study of lymphocystis disease in skin of gilthead seabream, Sparus aurata L.

Abstract

A battery of horseradish peroxidasecorijugated lectiris (Con A, WGA arid DBA). as well as coriventional histochemical techniques (PAS. saponification, Alcian Blue pH 0.1 , 1. 2.5. chlorhydric hydrolisis. sialidasc, Bromophenol blue, Tioglycollate reduction and Ferric-ferricyanide-FeIlI) were used to study the coritent and distribution of carbohydrates, proteins and glycoconjugatc sugar residues on the skin and on the lymphocystis-infected cells of gilthead seabrcain, Spcrrus uurntcr. Variable ari-iounts of glycoproteins containing sialic acid, N-acetyl-Dglucosainine, N-acetyl-D-galactosarnine; mannose andlor glucose residues were observed in the cuticle and mucous cells of the c o r ~ o r a ls kin. tails and f ins . ~ ~ Germinative and epithelial cells of the epidermis contained glycogen. proteins. carboxylated groups, as well as glycoproteins with mannose andlor glucose and N-acetyl-U-galactosamine residues. Hyaline capsule of the mature lyniphocystis-infected cells was strongly stained with PAS, Alcian Blue (pH 0.5 and 2.5) and weakly positive with Alcian Blue (pH 1 ) . Con A reacted with the granular cytoplasm, specially around hyaline capsule. and with the basophilic intracytoplasinic inclusions developed in mature lymphocystis-infected cells of Spcrrrrs crlirntu skin. These sugar residues (niannose andlor glucose), as well as N-acetyl-Drrlucosamine andlor sialic acid and N-acetvl-D- L galactosamine were not detected in the hyaline capsule of the lyr.iphocysti5 disease.