Expression and promoter activity of endogenous retroviruses in the Olive flounder (Paralichthys olivaceus)

Olive flounder (Paralichthys olivaceus) is regarded as one of economical fish species in the world. Genome information of Olive flounder has been revealed by next generation sequencing. Endogenous retroviruses (ERVs) as a member of transposable elements have been involved in functional roles of various genes in variety organisms. In this study, we identified an Olive flounder ERV (OF-ERV5) using RepeatMasker program, and examined expression pattern of pol gene of OF-ERV5, which indicated the high expression in two kidney samples (head kidney and body kidney). In addition, the 5′LTR sequences of OF-ERV5 are cloned into pGL4.11 vectors to confirm promoter activity. Luciferase assay indicated that the OF-ERV5_LTR showed promoter activity in both HepG2 and HINAE cell lines. These data could be of great use for further study to understand biological function of transposable elements in Oliver flounder.