Relationship between the induction of proteins in the HSP70 family and thermosensitivity in two species of Oryzias (Pisces)

A cultured fish cell line, CE, derived from Oryzias celebensis, which lives in a tropical zone, was more heat-resistant than the OL32, which were derived from the Japanese medaka, Oryzias latipes which lives in a temperate zone. Protein synthesis in OL32 cells was also more heat-sensitive than that in CE cells. The relative levels in proteins of the HSP70 family and the ability of cells to tolerate severe heat treatment after a conditioning heat treatment were examined. Twenty-four hours after conditioning heat treatment, both cell lines retained thermotolerance even though three proteins in the HSP70 family had returned to their control levels.