Temperature stress response of heat shock protein 90(Hsp90)in the clam Paphia undulata

The Heat shock proteins(HSPs)are a group of molecular chaperones that play a crucial role in cell response to various stresses.A full-length cDNA of the heat shock protein 90(PuHsp90)was cloned and sequenced from the clam Paphia undulata.Phylogenetic analysis revealed that PuHsp90 grouped with the Hsp90 from other metazoan species.Expression of PuHsp90 was highly detected in the gonad,followed by digest gland,gills and heart but was found poorly expressed in mantle,adductor muscle and hemocytes.After a heat shock stress at 32℃up-regulation of PuHsp90 was detected in the mantle,adductor muscle,gills and hemocytes.Maximal expression levels occurred at 4 h after the heat shock and up-regulation is indicative of protein denaturation and of an increase in energy consumption.In contrast after the heat shock,PuHsp90 was continuously down-regulated in the digestive gland and in the gonad suggesting modifications of the biochemical pathways and energy budgets involved in the synthesis of other protein,such as catalase and of other Hsp proteins.These results reveal that PuHsp90 may play an important role in the clam response to a temperature stress.