Environmental regulation of gene expression. In vitro translation of winter flounder antifreeze messenger RNA.

The serum of winter flounder contains a group of antifreeze peptides which lower the freezing point of their body fluid in the winter. These antifreeze peptides disappear from their serum in the summer when the water temperature rises. Messenger RNA isolated from the liver of flounder collected in January directs the synthesis of predominantly one protein in an in vitro protein synthesis system. This protein can be precipitated by the antiserum made from the purified antifreeze peptides and was identified as the precursor(s) of these peptides. There is a seasonal variation in the concentrations of mRNA coding for the antifreeze peptides in the liver which can be correlated with the appearance and disappearance of these peptides in the serum. However, the changes in the levels of mRNA occur much sooner than the changes in the levels of antifreeze peptides in the serum, suggesting that an additional control mechanism might have taken place at the translational level.