Katz Uri, Rozman Alexander, Gabbay Shosh
Department of Biology, Technion, Israel Institute of Technology Haifa, Israel.
J Exp Zool A Comp Exp Biol. 2003 Jul 1;298(1):1-9. doi: 10.1002/jez.a.10258.
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.
在东方铃蟾皮肤上皮细胞的自然个体发育过程中，研究了主动钠（Na⁺）转运的起始以及氯离子（Cl⁻）电导（G(Cl)）的激活情况。同时测试了包括带三蛋白和花生凝集素结合在内的结构特征，并尝试建立结构与功能的关系。根据发育阶段的外部形态，将所研究的22个标本按照泰勒 - 科尔罗斯标准表分为两个蝌蚪期、三个幼年期和两个成年期。跨上皮电势的起始和电导的下降突然发生，与蝌蚪在发育约第 XXI 阶段变态为幼体的高潮期一致。氨氯地平敏感的钠（Na⁺）转运在第 XXIII 阶段稍晚出现，随后出现激活的氯离子（Cl⁻）电导G(Cl)。平行的结构检查表明，随着蝌蚪外皮转变为成年上皮，变态时皮肤MR细胞出现，并且可能与激活的G(Cl)的出现有关。它在时间上与MR细胞中带三蛋白的出现无关。我们的研究结果支持G(Cl)与MR细胞的关联，而带三蛋白可能只是G(Cl)的一个必然结果，对其表现不一定是必需的。
