Gilthead seabream (Sparus aurata) vitellogenin: purification, partial characterization, and validation of an enzyme-linked immunosorbent assay (ELISA).

VTG was purified from seabream Sparus aurata plasma by ion exchange chromatography on a DEAE-Sepharose column. The vitellogenin was characterized and its properties were determined. The molecular mass of the native form, obtained by Sephadex G-200 column, was around 450 kDa, whereas an apparent molecular mass of 180 kDa was detected by electrophoresis under denaturing and reducing conditions, suggesting a dimeric form for the native protein. The presence of carbohydrates was determined using concanavalin A, while the presence of phosphate groups was detected by Stains-all, a cationic stain. These data together with the sex specificity, the estrogen inducibility, and the cross-reactivity of the abVTG against the major yolk proteins identifies this protein as vitellogenin. The validated ELISA was used for a rapid and reliable measurement of plasma VTG changes related with those of estradiol-17beta in female broodstock. Copyright 1998 Academic Press.