Ecdysone receptor gene from the freshwater prawn Macrobrachium nipponense: Identification of different splice variants and sexually dimorphic expression, fluctuation of expression in the molt cycle and effect of eyestalk ablation

Abstract

The full-length cDNA of an ecdysone receptor gene (MnEcR) from Macrobrachium nipponense was cloned and the expression of the gene was investigated. MnEcR maintained a relatively low expression level in the early stages of embryos, but from nauplius stage, a steady increase in MnEcR expression was detected, it had the highest expression level in zoea stage. MnEcR was highly expressed in the hepatopancreas and gills among ten different tissues examined. MnEcR was rapidly upregulated in the premolt stage and rapidly downregulated in the postmolt stage. The expression of MnEcR was remarkably downregulated after eyestalk ablation in M. nipponense. An 18-amino-acid insertion/deletion and a 49-amino-acid substitution were found in the coding region of MnEcR, resulting in four splice variants: MnEcR-L1, -L2, -S1 and-S2. The expression of four splice variants of MnEcR in gonads was investigated using RT-PCR. Interestingly, the expression patterns of these splice variants differed between males and females. The dominant splice variants in testis were MnEcR-S1 and -S2, while in ovary they were MnEcR-L1 and -S2, indicating specific roles for these splice variants in male and female individuals.