Vitellogenin and Its mRNA Induction by $Estradiol-17\beta$ in the Primary Culture of Hepatocytes in the Rainbow Trout, Oncorhynchus mykiss

Vitellogenin (VTG) and VTG mRNA induction by were examined in the primary cultures of hepatocyte in the rainbow trout. Hepatocytes were precultured for 2 days, then was added and cultured for another 5 days. Media and hepatocytes were then analyzed by electrophoresis and Northern blotting for VTG and VTG mRNA, respectively. The hepatocytes were formed a few aggregates within 5 days without further spreading to a monolayer. Cell viability and high DNA content were maintained during the incubation. The hepatocyte culture with E2 induced a weak VTG band at a molecular weight of 175kDa on Day 2 after addition. The relative amount of VTG was expressed in percentage of total protein concentrations. VTG was gradually increased as on Day 2, on Day 4 and on Day 5. VTG mRNA band was detected at about 6.6 kb in the culture with at day 1 of culture. The level of VTG mRNA expression linearly increased with time until Day 5 (r=0.97).