The acquisition of thermal tolerance in larvae of calpodes ethlius (lepidoptera) and the in situ and in vitro synthesis of heat-shock proteins.

Larvae of Calpodes ethlius (Lepidoptera) reared at 22 degrees C die after 1 h at 45 degrees C, but they acquire the ability to tolerate 1 h at 45 degrees C if they are first exposed to 37 degrees C for 1 or 2 h. Incubation of intact larvae at 37 degrees C for 1 h induces the new and (or) enhanced synthesis of a similar family of polypeptides (relative masses (MrS) approximately 22 000) in all tissues examined (silk gland, fat body, wing discs, central nervous system, and muscle). When these same tissues are cultured at 37 degrees C for 1 h, the new and (or) enhanced synthesis of at least 5 polypeptides (MrS approximately 95 000, 81 000, 74 000, 26 000, and 22 000) is evident. The more dramatic response elicited from cultured tissues by heat shock results, presumably, from the added stress of dissection. The new and (or) enhanced synthesis of polypeptides with MrS of approximately 22 000 by tissues of intact larvae, incubated at 37 degrees C for 1 h, may be related to the acquisition of thermal tolerance by similarly treated larvae. These results suggest that the induced synthesis of these polypeptides is an integral part of a ubiquitous molecular mechanism involved in the development of thermal tolerance.