The expression of the HSP90 gene in response to winter and summer diapauses and thermal-stress in the onion maggot, Delia antiqua.

The full-length Hsp90 cDNA in Delia antiqua was cloned and sequenced. The deduced polypeptide comprised 717 amino acid residues, with a molecular mass of 82 140 Da. Summer- and winter-diapauses both elevated HSP90 transcript levels in D. antiqua pupae. Levels gradually increased with time in summer diapausing pupae whereas levels fluctuated in winter diapausing pupae. Cold- and heat-stressing summer- and winter-diapausing individuals further elevated HSP90 expression. mRNA levels gradually increased with time in summer diapausing pupae whereas levels decreased with time after an initial increase in winter diapausing pupae. HSP90 expression was also up-regulated following cold- and heat-stresses in non-diapausing pupae. Heat-stress gradually increased the mRNA level with time whereas cold-stress gradually decreased levels after an initial increase. These results suggest that the development and physiology of summer- and winter-diapauses, as monitored via variation in HSP90 transcript levels, can be substantial different.