LOW-TEMPERATURE PERSISTENCE OF TYPE-I ANTIFREEZE PROTEIN IS MEDIATED BY COLD-SPECIFIC MESSENGER-RNA STABILITY

In winter flounder, the! levels of type I antifreeze protein (AFP) and its mRNA vary seasonally by as much as 1000-fold, Elevated levels in the fall are prompted by the loss of long day-lengths, while higher sp ring temperatures correlate with AFP clearance, We have investigated t he role of temperature on AFP accumulation using transgenic Drosophila melanogaster by expressing multiple AFP genes under control of the he at-inducible hsp70 promoter, AFP and AFP mRNA persisted far longer in flies reared at 10 degrees C compared to 22 degrees C. This difference appears to be mediated by cold-specific mRNA stability since no such temperature effect was observed with either an endogenous heat-inducib le mRNA or a constitutively expressed mRNA.