Meeting Abstract

108.8  Tuesday, Jan. 7 10:00  Effects of Salinity and Hormone Treatment on Gill Claudin Expression and Localization in Rainbow Trout (Oncorhynchus Mykiss) BUJAK, JK*; BOLLINGER, RJ; MADSEN, SS; TIPSMARK, CK; Univ. of Arkansas, Fayetteville; Univ. of Arkansas, Fayetteville; Univ. of Southern Denmark, Odense; Univ. of Arkansas, Fayetteville jkbujak@uark.edu

In the branchial epithelium of euryhaline fish, permeability changes are critical during acclimation to changes in salinity. Claudin proteins are integral components of tight junctions and control paracellular resistance and cation selectivity. From previous studies in our laboratory it is clear that claudin-10e, -28a and -30 have the highest expression in gill tissue of rainbow trout. In the present studies we examined the localization of these three proteins in the gill tissue to develop our knowledge about their physiological role. Specific antibodies were developed and validated for Western blot. Localization of claudin-10e, -28a and -30 were then examined in freshwater and seawater acclimated rainbow trout. Immunofluorescence microscopy showed localization of claudin-10e exclusively in Na,K-ATPase rich cells in the filament of SW fish. This is in accordance with our previous observations that seawater (SW) transfer strongly stimulates claudin-10e expression. Furthermore localization in SW ionocytes is consistent with in silico analysis suggesting that this isoform forms cation pores and thus may be instrumental in creating the leaky pathway for sodium. Claudin-30 was found deeper in the gill filament and was absent from Na,K-ATPase rich cells while Claudin- 28a was detected in both pavement cells and ionocytes. The effect of osmoregulatory hormones on claudin-10e, -28a and -30 is currently under investigation and will be presented.