Antifreeze protein gene transcription in winter flounder is not responsive to temperature

Although the endogenous rhythm of antifreeze protein gene expression in winter flounder is primarily regulated through the pituitary, the effect of water temperature on the annual cycle is poorly understood. In order to determine the specific effects of temperature on antifreeze gene transcription we did a series of experiments with intact and hypophysectomized winter flounder kept at various temperature regimes. Our results demonstrate that temperature shifts do not induce or suppress antifreeze gene transcription as determined by "run-on" transcription assays or by Northern blot analysis of liver mRNA in hypophysectomized flounder. However, warm temperature reduces the amount of antifreeze protein in the plasma, and apparently reduces the half-life of antifreeze protein mRNA.