Purification of vitellogenin from smooth flounder ( Pleuronectes putnami) and measurement in plasma by homologous ELISA

Male smooth flounder ( Pleuronectes putnami) were induced to produce vitellogenin (VTG) by injection of 17β-estradiol (E2). Anion exchange chromatography of precipitated plasma from E2-injected resulted in a single peak consisting of VTG. Smooth flounder VTG has an approximate molecular mass of ∼520 kDa, determined by gel filtration with molecular weight standards. Purified VTG was used to develop a homologous enzyme-linked immunosorbent assay (ELISA). The flounder VTG ELISA is an indirect antigen competition assay with a detection limit of 15 ng·ml −1 and a useful range of 30–950 ng·ml −1 of diluted sample. Intra- and inter-assay precision (as %CV, n=7) ranged from 1.3% to 6.0% and 5.1%, respectively. The ELISA was evaluated using plasma samples collected from a smooth flounder population captured in the Saint Lawrence Estuary. The ELISA is sensitive enough to differentiate males and non-vitellogenic females from vitellogenic individuals during early vitellogenesis.