Heat‐shock protein 90 is down‐regulated during pupal diapause in the flesh fly, Sarcophaga crassipalpis, but remains responsive to thermal stress

Abstract Heat‐shock protein 23 (hsp23) and hsp70 are both known to be strongly up‐regulated during pupal diapause in the flesh fly Sarcophaga crassipalpis . This prompted us to investigate whether hsp90 was also up‐regulated during diapause. To test this possibility, we developed a partial clone of a hsp90 family member for use as a probe in Northern blot hybridization. Both high and low temperature exposure up‐regulated hsp90 transcripts in nondiapausing individuals. In contrast to hsp23 and hsp70 , hsp90 was down‐regulated following entry into diapause, and returned to prediapause levels after diapause termination. The response of hsp90 to heat shock and cold shock remained intact during diapause: both shocks evoked elevated expression. The results indicate differential regulation of hsps during diapause and in response to thermal injury inflicted on diapausing pupae.