Lectin binding pattern and band 3 localization in toad skin epithelium and the effect of salt acclimation

Abstract

Seven lectins were employed to localize glycoconjugates in the skin of a toad (Bufo viridis). Each of the lectins exhibited a particular, specific and selective binding pattern. Peanut lectin (PNA) and WGA bound to mitochondria-rich (MR) cells, but WGA bound also abundantly, in the dermis. Band 3-like protein, as indicated by the reaction with polyclonal anti band 3 antibody, was localized exclusively in MR cells. Ionic acclimation (200 mmol/L NaCl, or 50 mmol/L KCl) affected profoundly the binding pattern of the lectins. High NaCl acclimation resulted also in diminishing anti band 3 antibody binding, whereas in skins of KCl-acclimated toads the staining remained similar to the control. The binding of WGA but not PNA, corresponded with the same cells that stained with anti band 3 antibody. PNA in concentration of > 10 micrograms/mL reduced reversibly, both the resting and activated Cl- conductance by 25-30%. Based on differential binding of band 3, WGA and PNA, these observations provide conclusive verification of the presence of at least two populations of MR cells in the toad skin epithelium. It is suggested that the PNA positive MR cells may correspond to a beta-type MR cell. The information can be used to study molecular mechanisms that are involved in ionic acclimation.

Glycoconjugate localization in larval and adult skin of the bullfrog, Rana catesbeiana: A lectin histochemical study

“…These cells are important in facilitating chloride movement through the epidermis (e.g., Katz and Gabbay, 1993). In R. catesbeiana adults, such cells stained strongly with UEA 1 and SBA; staining with one or both of these lectins was reported previously for many other species, including R. ridibunda, R. perezi, Bufo viridis, Xenopus laevis, Hyla arborea, and Bufo marinus (Villalba et al, , 1993aKatz et al, 1997;Zaccone et al, 1999). Although no WGA or PNA staining was detected in flask cells of R. catesbeiana, such cells did stain with WGA in B. viridis and B. marinus (Katz et al, 1997;Zaccone et al, 1999) and with PNA in B. viridis but not in many other species (Katz and 1 Danguy and Genten, 1990.…”

“…Yet sites of glycoconjugates have been reported in skin (particularly the epidermis) of other anurans by the use of lectins that bind to specific terminal sugar residues of glycoconjugates, e.g., including the ranids R. perezi Villalba and Navas, 1989;Villalba et al, 1993aVillalba et al, ,b, 1994, R. rugosa (Choi et al, 1997), and R. ridibunda and R. pipiens Zaccone et al, 1999). In addition, sites of glycoconjugates have been identified in aquatic Xenopus laevis Genten and Danguy, 1990;Amano et al, 1995;Zaccone et al, 1999) and several species of terrestrial frogs and toads (Budtz and Spies, 1989;Genten and Danguy, 1990;Gabbay et al, 1992;Faszewski and Kaltenbach, 1995;Katz et al, 1997Katz et al, , 2003Zaccone et al, 1999). The few studies carried out on skin of tadpoles involve R. perezi (Villalba and Navas, 1989;Gabbay et al, 1992;Villalba et al, 1993b), R. dalmatina (Faraldi et al, 1996), X. laevis (Amano et al, 1995), Pelobates syriacus (Gabbay et al, 1992;Katz et al, 2003), and Ceratophrys ornata (Faszewski and Kaltenbach, 1995).…”

“…Gabbay, 1993;Katz et al, 1997Katz et al, , 2003Zaccone et al, 1999). In R. catesbeiana, UEA 1 and SBA may be considered as markers for flask cells.…”