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 approximately 215 kDa and approximately 69 kDa, respectively. In SDS-PAGE, Chg H and Chg L separated to positions corresponding to approximately 51 kDa and approximately 44 kDa, respectively. The mass of intact VgB was approximately 530 kDa and resolved into a polypeptide of approximately 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-17beta (E(2)), 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 E(2) 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.