Glycoconjugates in the branchial mucous cells of Cynoscion guatucupa (Cuvier, 1830) (Pisces: Sciaenidae)

Abstract

This study examines the mucous cells from the gills of the stripped weakfish Cynoscion guatucupa. The glycoconjugates (GCs) were identified with: (1) oxidizable vicinal diols; (2) sialic acids and some of their chain variants, C7, C8 or C9; (3) sialic acid residues with O-acyl substitution at C7, C8 or C9; (4) carboxyl groups and (5) sulphate groups. The presence of sugar residues in the oligosaccharide side chain of glycoconjugates was investigated by means of a battery of seven biotinylated lectins. One type of mucous cell was identified in the primary and secondary lamellae, the secretory content of which evidenced neutral, sulphated and sialylated glycoconjugates. The distribution pattern of the mucus was identical in the primary and secondary lamellae. PNA had the most staining in the mucous cell content, while UEA-I had the least, as it was completely negative. Con-A showed weak to no staining and WGA showed weak to moderate staining. The reactions to DBA, SBA and RCA-I were moderate. This work clearly demonstrates the heterogeneity of the mucous cell glycoconjugates, which could be involved in various functions, such as lubrication, protection, inhibition of microorganisms and a role in ion regulation and diffusion.