Effects of ecdysone agonists on the expression of EcR, USP and other specific proteins in the ovaries of the codling moth ( Cydiapomonella L.)

Abstract

Tebufenozide and methoxyfenozide have been previously shown to significantly reduce fecundity and cause vitellogenin accumulation in hemolymph of the codling moth Cydia pomonella L. In the present study, the effects of these ecdysone agonists, tebufenozide and methoxyfenozide, on the expression of ecdysone receptor (EcR), ultraspiracle protein (USP) and other proteins in the ovaries of C. pomonella L., were investigated at both the translational and/or transcriptional levels with an aim to elucidate the mechanisms by which the fecundity was reduced. Western and Northern blot analyses revealed that the expression of a 65 kDa (p65) EcR, and 60 and 64 kDa (p60 and p64) USP proteins were enhanced by tebufenozide and methoxyfenozide at both transcriptional and translational levels. Northern blot analysis indicated that the p65 EcR protein is encoded by EcRB1 transcript and that the p60 and p64 USP bands were the products of USP-1 transcript. Immunoprecipitation assays demonstrated that both the p60 and p64 USP coprecipitated with the p65 EcR and that p64 was a dominant USP to form complex with EcR. In addition, several other specific proteins were also identified and their expressions affected by the agonists. The data suggest that the ecdysone agonists regulate, via the EcR/USP complex, the expression of these specific proteins that might eventually lead to the inhibition of fecundity in the codling moth.