Skin epithelial transport and structural relationships in naturally metamorphosing Pelobates syriacus

Abstract

The onset of active Na(+) transport and activated Cl(-) conductance (G(Cl)) across the skin epithelium of Pelobates syriacus was investigated during natural ontogenetic development. Structural features, including band three and Peanut lectin bindings were tested in parallel and structure-function relationships were attempted. The 22 specimens studied were divided into two tadpole, three juvenile, and two adult stages, corresponding to the Taylor-Kollros standard table, in accordance with external morphology of their developmental stage. Onset of transepithelial electrical potential and drop in conductance occurred abruptly, coinciding with metamorphosis climax of tadpoles into juveniles at about stage XXI of development. Amiloride-sensitive Na(+) transport occurred a little later at stage XXIII, followed by the appearance of activated Cl(-) conductance, G(Cl). Parallel structural examination showed that skin MR cells occurred upon metamorphosis, as the tadpole integument transformed into the adult epithelium and could be associated with the occurrence of activated G(Cl). It was not related temporally with the appearance of band three protein in MR cells. Our findings support the association of G(Cl) with MR cells, whereas band three may only be a corollary of G(Cl) and not necessarily essential for its manifestation.

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

“…More specifically, in the epidermis there is a dramatic increase in levels of Na ϩ -K ϩ -ATPases and the capacity to actively transport Na ϩ (Burggren and Just, 1992). There is also an increase in Cl -conductance correlated with an increase in the number of flask cells (Katz et al, 2003). These events, accompanied by changes in glycoconjugate localizations, reinforce the role of the skin in maintaining water balance in the adult bullfrog.…”

“…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).…”

“…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). Moreover, a comparison of lectin staining in dorsal and ventral skin has been made only in adult Xenopus and larval and adult C. ornata (Faszewski and Kaltenbach, 1995).…”

Metamorphic changes in localization of sugars in skin of the leopard frog, Rana pipiens

“…During metamorphic climax, both morphological and physiological changes occur in amphibian skin. For example, epidermal remodeling is accompanied by increases in Na 1 -K 1 -ATPase and in the active transport of Na 1 (Burggren and Just, 1992), as well as in Clconductance which is correlated with increased number of flask cells (Katz et al, 2003). Such changes are controlled by hormones secreted by a variety of endocrine glands.…”

“…We are not aware of any studies on lectin binding in larval skin of R. pipiens. However, there are such reports for larval skin of aquatic Xenopus laevis (Amano et al, 1995), semiaquatic Rana perezi (Villalba and Navas, 1989;Gabbay et al, 1992;Villalba et al, 1993), Rana dalmatina (Faraldi et al, 1996), and R. catesbeiana (Kaltenbach and Faszewski, 2002;Kaltenbach et al, 2004), as well as terrestrial Pelobates syriacus (Gabbay et al, 1992;Katz et al, 2003) and Ceratophrys ornata (Faszewski and Kaltenbach, 1995). Moreover, comparisons of lectin binding in skin from different body regions have been made in only a few species, e.g., adult X. laevis , larval and adult C. ornata (Faszewski and Kaltenbach, 1995), and larval and adult R. catesbeiana (Kaltenbach and Faszewski, 2002;Kaltenbach et al, 2004).…”