Dynamics of gene expression responses for ion transport proteins and aquaporins in the gill of a Euryhaline Pupfish during freshwater and high salinity acclimation

Physiological and Biochemical Zoology
By: , and 

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Abstract

Pupfishes (genus Cyprinodon) evolved some of the broadest salinity tolerances of teleost fishes, with some taxa surviving in conditions from freshwater to nearly 160 ppt. In this study, we examined transcriptional dynamics of ion transporters and aquaporins in the gill of the desert Amargosa pupfish (Cyprinodon nevadensis amargosae) during rapid salinity change. Pupfish acclimated to 7.5 ppt were exposed to freshwater (0.3 ppt), seawater (35 ppt), or hypersaline (55 ppt) conditions over 4 h and sampled at these salinities over 14 d. Plasma osmolality and Cl concentration became elevated 8 h after the start of exposure to 35 or 55 ppt but returned to baseline levels after 14 d. Osmolality recovery was paralleled by increased gill Na+/K+-ATPase activity and higher relative levels of messenger RNAs (mRNAs) encoding cystic fibrosis transmembrane conductance regulator (cftr) and Na+/K+/2Cl cotransporter-1 (nkcc1). Transcripts encoding one Na+-HCO3 cotransporter-1 isoform (nbce1.1) also increased in the gills at higher salinities, while a second isoform (nbce1.2) increased expression in freshwater. Pupfish in freshwater also had lower osmolality and elevated gill mRNAs for Na+/H+ exchanger isoform-2a (nhe2a) and V-type H+-ATPase within 8 h, followed by increases in Na+/H+ exchanger-3 (nhe3), carbonic anhydrase 2 (ca2), and aquaporin-3 (aqp3) within 1 d. Gill mRNAs for Na+/Cl cotransporter-2 (ncc2) also were elevated 14 d after exposure to 0.3 ppt. These results offer insights into how coordinated transcriptional responses for ion transporters in the gill facilitate reestablishment of osmotic homeostasis after changes in environmental salinity and provide evidence that the teleost gill expresses two Na+-HCO3 cotransporter-1 isoforms with different roles in freshwater and seawater acclimation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Dynamics of gene expression responses for ion transport proteins and aquaporins in the gill of a Euryhaline Pupfish during freshwater and high salinity acclimation
Series title Physiological and Biochemical Zoology
DOI 10.1086/700432
Volume 91
Issue 6
Year Published 2018
Language English
Publisher University of Chicago press
Contributing office(s) Leetown Science Center
Description 24 p.
First page 1148
Last page 1171