Branchial Expression Patterns of Claudin Isoforms in Atlantic Salmon During

• Main Authors: Seawater Acclimation, Ck Tipsmark, P Kiilerich, To Nilsen, Loe Ebbesson, So Stefansson, Ss Madsen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Atlantic salmon
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.326.2622; http://ajpregu.physiology.org/content/early/2008/03/05/ajpregu.00915.2007.full.pdf

In euryhaline teleosts, permeability changes in gill epithelia are essential during acclimation to changed salinity. This study examined expression patterns of branchial tight junction proteins called claudins, which are important determinants of ion selectivity and general permeability in epithelia. We identified Atlantic salmon genes belonging to the claudin family by screening expressed sequence tag libraries available at NCBI and classification was performed with aid of maximum likelihood and neighbour-joining analysis. In gill libraries, five isoforms (10e, 27a, 28a, 28b and 30) were present and QPCR analysis confirmed tissue-specific expression in gill when compared to kidney, intestine, heart, muscle, brain and liver. Expression patterns during acclimation of freshwater salmon to seawater (SW) and during the smoltification process were examined. Acclimation to SW reduced the expression of claudin 27a and claudin 30 but had no overall effect on claudin 28a and claudin 28b. In contrast, SW induced a 4-fold increase in expression of claudin 10e. In accord, a peak in branchial claudin 10e was observed during smoltification in May, coinciding with optimal SW tolerance. Smoltification induced no significant changes in expression of the other isoforms. This study demonstrates the expression