LECTIN HISTOCHEMISTRY OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) GILL ANDSKIN

In order to characterize the glycoconjugate residues in skin and gills of the adult rainbow trout, the binding pattern of five biotinylated lectins with different carbohydrate specificities was examined. In the skin, mucous cells revealed binding sites for PNA and SBA; filament-c ontaining cells were additionally labelled with Con A. However, the ba sal cell layer showed no reaction. In the gill, subpopulations of muco us cells reacted with Con A, PNA, SBA and UEA-I. This broader spectrum of glycoconjugates in gill mucous cells compared with the epidermal m ucous cells could point to the additional function of gill mucus in io n and osmoregulation. Lectin binding sites were less common in the res piratory epithelial cells of the secondary lamellae than in those of t he primary lamellae. Chloride cells revealed mannose, galactose and fu cose residues. Immature chloride cells, as indicated by a comparison w ith Na+/K+ ATPase immunolabelling, reacted with Con A; subpopulations of them reacted with PNA, SBA and UEA-I. The results form the basis fo r further investigations in which these cell populations can be analys ed under different environmental conditions.