Role of clc2b chloride channel in chloride regulation of zebrafish (Danio rerio).

Abstract

Osmotic and ionic homeostasis in the body fluid is important for vertebrates including teleost fish, and this is mainly achieved in gill/skin ionocytes in fish. Chloride is the most abundant anion in animal tissue and plasma and participates in many physiological processes. Comparing with the regulation mechanisms of other ions that have been studied in details in zebrafish, the chloride ion regulatory pathways are less understood. In the present study, we cloned out 11 members of clc chloride channels in zebrafish. Several clc members were found to be expressed in the gills of zebrafish by RT‐PCR; however, only the mRNA of clc2b was localized by in situ hybridization in the zebrafish embryonic yolk sac and adult fish gill with an ionocyte pattern. Combination of clc2b in situ hybridization and zebrafish sodium chloride cotransporter‐like 2 (zNCC‐like 2) immunocytochemistry indicated that 2 transporters are co‐expressed on the same ionocyte. Furthermore, comparison of chloride content of clc2b morpholino knockdown and wild‐type zebrafish embryos showed significant difference. Altogether, the data suggested that clc2b plays an important role in zebrafish chloride regulation.