Immunochemical identification of female-specific serum protein, vitellogenin, in the medaka, oryzias latipes (teleosts)

1. 1. Three female-specific serum proteins, denoted tentatively as FS-1, FS-2 and FS-3, were identified in female serum of medaka, Oryzias latipes, at breeding season as well as in serum of male treated with estrogen, by crossed immunoelectrophoresis using antiserum to egg yolk extracts. 2. 2. Two proteins, FS-2 and FS-3, showed iron-binding activity, similar to vitellogenin of rainbow trout, chum salmon or Japanese eel. FS-1, on the other hand, had no such activity but was detected even in immature female serum. 3. 3. Occurrence of these three proteins in female serum closely correlated with the histological changes of ovarian maturation.