Small heat shock protein Hsp67Bc plays a significant role in cold stress tolerance.

Hsp67Bc in is a member of the small heat shock protein family, the main function of which is to prevent the aggregation of misfolded or damaged proteins. Hsp67Bc interacts with Starvin and Hsp23, which are known to be a part of the cold stress response in the fly during the recovery phase. In this study, we investigated the role of the gene in the cold stress response. We showed that in adult , expression increases after cold stress and decreases after 1.5 h of recovery, indicating the involvement of Hsp67Bc in short-term stress recovery. We also implemented a deletion in the gene using imprecise excision of a -element, and analysed the cold tolerance of null mutants at different developmental stages. We found that null homozygous flies are viable and fertile but display varying cold stress tolerance throughout the stages of ontogenesis: the survival after cold stress is slightly impaired in late third instar larvae, unaffected in pupae, and notably affected in adult females. Moreover, the recovery from chill coma is delayed in null adults of both sexes. In addition, the deletion in the gene caused more prominent up-regulation of following cold stress, suggesting the involvement of in compensation of the lack of the Hsp67Bc protein. Taken together, our results suggest that Hsp67Bc is involved in the recovery of flies from a comatose state and contributes to the protection of the fruit fly from cold stress.