Cloning and expression of guanylin-like peptides in teleost fish

Homologues of the guanylin peptide family are expressed in teleost fish. Using the eel as a model euryhaline species, cDNAs for three peptides, guanylin, uroguanylin, and renoguanylin, were cloned and found to be expressed within both renal and intestinal epithelia. Seawater (SW) acclimation resulted in upregulation of uroguanylin mRNA expression in the intestinal epithelia of both immature "yellow" and sexually mature "silver" eels. SW acclimation also resulted in an increase in guanylin mRNA in silver eel intestine, whereas there was no change in renoguanylin mRNA expression under any condition. No changes in expression were found in the kidney following SW acclimation.