Cloning of the Ecdysone Receptor Gene from the Chinese Mitten Crab, Eriocheir sinensis, and Sexually Dimorphic Expression of Two Splice Variants

The ecdysone receptor (EcR), a member of the nuclear receptor superfamily, plays an important role in molting in crustaceans and insects. Here, we report the cloning of the full-length cDNA of the EcR gene from Eriocheir sinensis (EsEcR). A 477 bp alternatively spliced intron was identified, with two splice variants. One, EsEcR-L, is 2522 bp long and encodes a 577 amino acid protein. The second, EsEcR-S, is 2045 bp long and encodes a 422 amino acid protein. Among eight different tissues, the expression of EsEcR was highest in the hepatopancreas and lowest in the heart. EsEcR was expressed during different embryonal developmental stages, and its expression reached the highest level at the original zoea stage. EsEcR-L was specifically expressed in testis among eight examined tissues and was also the predominantly expressed form in testis, while in other tissues the predominantly expressed form was EsEcR-S, indicating different roles of these splice variants in males and females. EsEcR-L was also expressed in embryos. The responses of EsEcR and EsEcR-L after eyestalk ablation (ESA) were investigated in four tissues, including hepatopancreas, muscle, testis, and ovary. The expression of EsEcR was upregulated after ESA in hepatopancreas, muscle, and ovary, while the expression of EsEcR-L was downregulated after ESA.