Cold- and heat-shock induction of new gene expression in cultured amphibian cells.

Exposing primary epidermal cell cultures from the American bullfrog Rana catesbeiana to elevated (greater than or equal to 32 degrees C; heat shock) or depressed (less than or equal to 5 degrees C; cold shock) temperatures for a short time results in the new and (or) enhanced synthesis of a 65 000 dalton (isoelectric point (pI) 6.7-6.9) polypeptide. With increasing temperature, a marked decrease in the synthesis of polypeptides observed at the control temperature (22 degrees C) and the new and (or) enhanced synthesis of another polypeptide with a relative mass of 25 000 and a pI of 6.7-6.9 is noted. Following a 1-h incubation at 34 degrees C, at least 4 h of recovery (at 22 degrees C) is required for primary epidermal cultures to resume their preinduction pattern of protein synthesis. Similar studies using an established adult kidney epithelial cell line from the African claw-toed frog Xenopus laevis demonstrate that cells from this organism respond to heat shock but do not respond to cold shock. Xenopus cells respond to heat shock by the new and (or) enhanced synthesis of at least five polypeptides. In vitro translation of the mRNAs from heat-shocked Xenopus cells suggests that the heat-shock mRNAs from these cells are preferentially transcribed and translated during thermal stress.