Temperature ranges over which rainbow trout fibroblasts survive and synthesize heat‐shock proteins

Abstract

Cultures of the rainbow trout fibroblast cell line RTG‐2 withstood temperatures from 0°C to 28°C. At 0°C and 28°C, no prolifertion occurred, but cells persisted for at least 7 days. If the cultures were placed back at 22°C, proliferation returned to normal in those that had been kept at 0°C but was reduced in cultures that had been kept at 28°C. Above 28°C, cultures survived for only short periods. If RTG‐2 cells that were grown routinely at 22°C were shifted to 26, 28, and 30°C, heat shock proteins (hsps) of 100, 87, 70, 68, 60, 39, 27, and 19 kilodaltons were synthesized. Synthesis was most pronounced at 28°C, and at this temperature hsp synthesis was maximal by 2 hr and had returned to control levels by 36 hr. Individual hsps were synthesized maximally at slightly different times and temperatures, but under all conditions hsps 87 and 70 were most abundant. If cultures were shifted to 24°C or 32°C, hsp synthesis was not observed. Neither the placement of cultures at 5°C nor the shift of cultures that had been maintained at 0°C or 5°C back to 22°C induced the synthesis of hsps. However, cultures incubated at 5°C for 24 hr did synthesize hsps at 26°C, 28°C, and 30°C.