Choriogenin and vitellogenin in red lip mullet (Chelon haematocheilus):Purification, characterization, and evaluation as potential biomarkers for detecting estrogenic activity

Two vitelline envelope precursors (choriogenin H: Chg H; choriogenin L: Chg L) and an egg yolk precursor (vitellogenin B: VgB) were purified from red lip mullet. The mass of intact Chg H and Chg L were estimated to be ~ 215 kDa and ~ 69 kDa, respectively. In SDS-PAGE, Chg H and Chg L separated to positions corresponding to ~ 51 kDa and ~ 44 kDa, respectively. The mass of intact VgB was ~ 530 kDa and resolved into a polypeptide of ~ 185 kDa in SDS-PAGE. Specific antisera were raised against each purified protein and specific immunoassays were developed. When Chg H, Chg L and VgB were induced in the serum of immature mullet by injection with various doses of estradiol-17β (E2), VgB exhibited the most sensitive response exhibiting high variation in its induced levels. The variation in induced levels of Chg H and L was relatively minimal although induction required higher doses of E2 than with VgB. Serum samples obtained from immature mullet populations collected from their natural habitat exhibited similar profiles in the levels of these proteins. The present study suggests that the utilization of multiple biomarkers holds great importance for the reliable and accurate evaluation of estrogenic activity in aquatic environments.