A divergent CFTR homologue: highly regulated salt transport in the euryhaline teleost F. heteroclitus

Am J Physiol. 1998 Mar;274(3):C715-23. doi: 10.1152/ajpcell.1998.274.3.C715.


The killifish, Fundulus heteroclitus, is a euryhaline teleost fish capable of adapting rapidly to transfer from freshwater (FW) to four times seawater (SW). To investigate osmoregulation at a molecular level, a 5.7-kilobase cDNA homologous to human cystic fibrosis transmembrane conductance regulator (hCFTR) was isolated from a gill cDNA library from SW-adapted killifish. This cDNA encodes a protein product (kfCFTR) that is 59% identical to hCFTR, the most divergent form of CFTR characterized to date. Expression of kfCFTR in Xenopus oocytes generated adenosine 3',5'-cyclic monophosphate-activated, Cl(-)-selective currents similar to those generated by hCFTR. In SW-adapted killifish, kfCFTR was expressed at high levels in the gill, opercular epithelium, and intestine. After abrupt exposure of FW-adapted killifish to SW, kfCFTR expression in the gill increased severalfold, suggesting a role for kfCFTR in salinity adaptation. Under similar conditions, plasma Na+ levels rose significantly after 8 h and then fell, although it is not known whether these changes are directly responsible for the changes in kfCFTR expression. The killifish provides a unique opportunity to understand teleost osmoregulation and the role of CFTR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological
  • Amino Acid Sequence
  • Animals
  • Calcium Channels / metabolism
  • Cyclic AMP / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / chemistry
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics*
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • DNA, Complementary / metabolism
  • Gene Expression
  • Humans
  • Killifishes
  • Molecular Sequence Data
  • Sequence Alignment
  • Water-Electrolyte Balance
  • Xenopus


  • CFTR protein, human
  • Calcium Channels
  • DNA, Complementary
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Cyclic AMP

Associated data

  • GENBANK/AF000271