Intrahepatic expression of genes encoding choriogenins: Precursor proteins of the egg envelope of fish, the medaka, Oryzias lapites

The time course and pattern of expression of the genes for choriogenin H and choriogenin L in the liver of the E₂-treated male fish was investigated according to the methods of dot blotting analysis and in situ hybridization. Four hours after the beginning of estrogen treatment (final concentration in rearing water: 100 ng ml^-1), expression of the choriogenins genes was induced in every parenchymal cell in the liver and the amounts of the gene transcripts were generally increased. As a primary step for analysis of the mechanism of the estrogen action, the amount of estrogen receptor and expression of its gene were examined in the liver of estrogen-treated male fish.