Publication:
Marshall, W.S., Breves, J.P., Doohan, E.M., Tipsmark, C.K., Kelly, S.P., Robertson, G.N. and Schulte, P.M. (2018). claudin-10 isoform expression and cation selectivity change with salinity in salt-secreting epithelia of F. heteroclitus J. Exp. Biol. 221, jeb168906. doi:10.1242/jeb.168906 In this highly collaborative project, we tested to see whether pore-forming Claudin-10 isoforms responded to salinity challenge. Indeed they did. In SW mostly Claudin-10d and -10e prevailed, whereas in 2xSW, Claudin-10c -10e and -10f predominated. The apparent difference is that -10c and -10f can form more stable ionic and hydrophobic bonds to hold the pore together in the high ionic strength 2xSW. Figure Right. Changes in mRNA abundance of branchial claudin-10 (A-D) and cystic fibrosis transmembrane conductance regulator (cftr) (E) transcripts in mummichogs after transfer from seawater (SW) to hypersaline SW (2SW; solid bars). Mean + S.E.M. (n = 10). Transcript abundance is presented as a fold-change from SW-to-SW controls (open bars). Transcript abundance of cldn-10c (A) and -10f (D) increased with hypersaline exposure (3 and 10 days), whereas cldn-10d (B) transcript abundance was unchanged and cldn-10e (C) mRNA abundance transiently increased at 1 and 3 days. Abundance of cftr mRNA increased significantly at 3 and 10 days (E). Significant differences between 2SW groups and controls are indicated (†P<0.05, ††P<0.01 and †††P<0.001), two-way ANOVA, followed by Tukey’s a posteriori tests, two tailed. Honours student Ellen Doohan did the ion selectivity experiments, while Jason Breves and I did the qPCR work on gill tissue from mummichogs from freshwater, seawater (SW) and hypersaline (2xSW) conditions. |