| Summary: | Permeability changes of the gill epithelium of euryhaline teleosts are imperative during salinity acclimation. This study examined the expression patterns of 5 claudin isoforms in the salmon gill. These are membrane proteins being major determinants of selective and gross tight junction permeability. Nucleotide sequences representing proteins of this family were identified in expressed sequence tag libraries from Atlantic salmon gill and classified according to the established teleosts nomenclature. Five isoforms: 10e, 27a, 28a, 28b and 30a, were identified in the gill, and tissue specific expression was confirmed by RT-QPCR. We examined the expression profile during the parr-smolt transformation (PST) in freshwater and during acclimation to sea water (SW). During PST, claudin 10e expression peaked in May, coinciding with optimal SW tolerance. The other claudin isoforms were not influenced during PST. SW-transfer induced a 5-fold increase in expression of claudin 10e, reduced the expression of 27a and 30a and had no overall effect on 28a and 28b isoforms. The study demonstrates for the first time that SW acclimation involves differential regulation of claudin gene expression in the salmon gill, some of which are induced in preparation to SW migration during smolting. We suggest discrete functional roles of the identified claudins in the gill.
|
|---|