An emerging literature suggests that natriuretic peptides (NPs) from the heart and brain may play a role in osmoregulation and cardiovascular physiology in fishes, as they do in mammals. However, current data are somewhat conflicting and are largely based on use of heterologous peptides and antibodies. We propose to undertake a series of protocols to clone and sequence the gene(s) for NPs in two species of fishes with quite dissimilar osmoregulatory problems and abilities (the toadfish and hagfish). Such studies will form the prelude for studies of the physiology of these peptides in fish physiology, and will enable a critical analysis of the evolution of the form and function of this important family of hormones.
