Identification and expression patterns of 20-hydroxyecdysone-responsive genes from Procambarus clarkii

Ecdysteroids play an important role in the regulation of molting process in crustaceans. The suppression subtractive hybridization (SSH) technique was employed to search for 20-hydroxyecdysone-responsive genes in the hepatopancreas of the crayfish Procambarus clarkii. Ninety-three putative expressed sequence tags were identified by SSH, including three immune response-related genes, two cell cycle and apoptosis genes, four respiration and energy metabolism genes, four transport-related genes, six metabolism-related genes, two stress response genes, and eight transcription and translation regulation genes. The expression levels of the examined genes were regulated by 20-hydroxyecdysone and varied in the hepatopancreas during the molting stages; data were confirmed by real-time PCR. RNAi of the ecdysteroid receptor had significant effects on the expression levels of 20-hydroxyecdysone-responsive genes. These differentially expressed genes identified by SSH will provide insight into the ecdysteroid signaling pathway in P. clarkii.