Characterization and expression profile of Vitellogenin gene from Scylla paramamosain

The full-length (7816 bp) cDNA of Vitellogenin (Vtg) encoding 2560 aa with an estimated molecular mass of 287.743 kDa was cloned from the green mud crab Scylla paramamosain. Semi-quantitative PCR (sq-PCR) revealed a specific expression pattern of Sp-vtg gene in ovaries and hepatopancreas. With the development of ovaries, the expression level of Sp-vtg gene showed an increasing trend both in ovaries and hepatopancreas, and the expression level of Sp-vtg gene in hepatopancreas and ovary was stable after stage IV. By in situ hybridization, the positive signals of Sp-vtg gene were detected in the cytoplasm of oocytes in stage I, in the follicle cell and the surrounding of the nucleus in stage III, and in the nucleus in stage V. Furthermore, the signals become stronger with the later development stages of ovary. Moreover, in situ hybridization analysis revealed that positive signals of Sp-vtg gene are present in the hepatopancreatic tubule, and the signals increase during the development, becoming the strongest in stage V. Our results indicate that both ovaries and hepatopancreas are sites of Vitellogenin gene synthesis in S. paramamosain.