Expression Analysis of Ecdysone Receptor and Ultraspiracle through Molting Period in Mysid Crustacean, Americamysis bahia

Ecdysteroids, primarily 20-hydroxyecdysone (20E), play a central role in the growth of arthropods. Molecular target of the ecdysteroids is known as a receptor complex composed of ecdysone receptor (EcR) and ultraspiracle (USP) protein. It is important to clarify the expression profile of EcR/USP in crustacean for understanding the endocrine disrupting effects of environmental xenobiotics on crustacean. However, despite EcR/USP has been characterized in insect, little is known about their complex functions in crustacean species. In this study, in order to gain better understanding of the mechanism of molting in mysid (Americamysis bahia), the molting stage-specific expressions of EcR/ USP were examined. The semi-quantitative RT-PCR analysis revealed that the expression level of the EcR increased during interand pre-molt stages (from 36 to 48 h after molting). This expression pattern correlated with the time of increasing titers of 20E, suggesting the essential role of EcR in the timing of molt. In the A. bahia exposed to 20E and nonylphenol for 8 h, the expression levels of EcR/USP mRNA were up-regulated when compared with controls. These results suggest that EcR/USP gene expression were associated with molting control in A. bahia, and may have been transcriptionally altered by exposure to nonylphenol.