CHARACTERIZATION OF VITELLOGENIN INDUCED BY ESTRADIOL-17-BETA IN PROTANDROUS BLACK PORGY, ACANTHOPAGRUS-SCHLEGELI

The objectives of this study were to isolate and characterize vitellog enin from plasma of estradiol-treated protandrous black porgy, Acantho pagrus schlegeli. Vitellogenin concentrations in plasma measured by a validated enzyme-linked immunosorbent assay (ELISA) were also compared . Two-year-old black porgy (n=20) were fed with estradiol-17 beta (4 m g kg(-1) of feed). Plasma was collected for purification of vitellogen in. Two forms of vitellogenin were found in plasma after chromatograph y on Sepharose CL-2B column and hydroxylapatite, and polyacrylamide ge l electrophoresis. Black porgy vitellogenins are phospho-lipo-glycopro teins based on their chemical staining properties. The apparent molecu lar weights of the two forms of vitellogenin were 636 kDa and 321 kDa, respectively. The amino acid composition of purified vitellogenin was also analyzed after acid hydrolysis. The presence of immunoreactive v itellogenin was identified in the plasma and mucus extract from contro l and estradiol-induced females on the basis of Western blotting. Seri al dilution of the plasma and mucus extract taken from estradiol-induc ed black porgy showed reactivity to an antiserum against lipovitellin in the ELISA, whereas mucus extract and plasma from male fish did not. Significantly higher concentrations of plasma vitellogenin were detec ted in estradiol-stimulated black porgy than in the control males.