Gene expression of heat-shock proteins (Hsp23, Hsp70 and Hsp90) during and after larval diapause in the blow fly Lucilia sericata

Genes encoding heat-shock protein 23 (Hsp23), Hsp70 and Hsp90 were cloned from Lucilia sericata to examine whether their expression is related to the regulation of its larval diapause. The level of all three Hsps mRNAs was consistently low irrespective of diapause status. These results indicate that expression of Hsp23, Hsp70 and Hsp90 is not regulated in response to diapause, in contrast to the flesh fly Sarcophaga crassipalpis that shows upregulation of Hsp23 and Hsp70 and downregulation of Hsp90 during its pupal diapause. On the other hand, Hsp90 transcripts were regulated developmentally in nondiapause larvae of L. sericata, i.e., they were at low levels after cessation of feeding but were considerably upregulated a day before pupariation, suggesting that Hsp90 is involved in a developmental process that occurs between the cessation of feeding and pupariation. When diapause larvae were transferred to all of the conditions that terminate diapause and allow postdiapause development, Hsp90 transcripts were promptly upregulated. These results indicate that Hsp90 may serve as an early marker to predict diapause termination in this species.