ATRIAL-NATRIURETIC-PEPTIDE GENE-EXPRESSION WITHIN INVERTEBRATE HEARTS

The present investigation was designed to (1) determine if atrial natr iuretic factor gene expression occurs within invertebrates as well as within vertebrates; (2) determine whether the product of this gene exp ression is the 126-amino-acid atrial natriuretic factor prohormone or some other molecular species; and (3) evaluate within the same inverte brates if the products of atrial natriuretic factor gene expression ar e released into their circulation. Utilizing a very sensitive RNase pr otection assay it was found that atrial natriuretic peptide gene expre ssion occurs within the heart of the oyster, Crassostrea virginica, an d within the heart of the blue crab, Callinectes sapidus, but was expr essed sevenfold less than in a vertebrate heart (i.e., rat, Rattus nor vegiucs). High-performance gel-permeation chromatography followed by N -terminal and C-terminal atrial natriuretic factor prohormone radioimm unoassays indicated that the molecular species synthesized within the oyster and blue crab hearts was the atrial natriuretic factor prohormo ne. The product(s) of this atrial natriuretic factor gene expression ( i.e., atrial natriuretic peptides) was found to be released into the c irculation, i.e., hemolymph, of both the oyster and the blue crab.