Plasma vitellogenin levels during the annual reproductive cycle of the female rainbow trout (Oncorhynchus mykiss): establishment and validation of an ELISA.

Rainbow trout, Oncorhynchus mykiss, vitellogenin (Vtg) was purified from plasma of E2-treated male by direct anion exchange chromatography and some of its biochemical characteristics were studied. Our results demonstrated that, under SDS-PAGE conditions, rainbow trout Vtg was composed of two molecular forms of 390 and 176 kDa representing, respectively, the dimeric form and the monomeric from of the molecule. The purified Vtg was used to raise a polyclonal antibody for Vtg (anti-Vtg).

Effects of flavonoids on aromatase activity, an in vitro study.

In the study, the inhibitory effect of flavonoids, including isoflavonic phytoestrogens, on the ovarian aromatase enzyme complex from the rainbow trout, Oncorhynchus mykiss, was assessed in vitro. Some of the compounds tested on fish were also tested on human placental aromatase activity as a comparison between the two sources of enzyme. It was found that flavone, dl-aminoglutethimide, apigenin, quercetin, 7,4'- dihydroxyflavone, alpha-naphthoflavone and equol were potent inhibitors of the ovarian aromatase activity in rainbow trout.

Interactions between phytoestrogens and human sex steroid binding protein.

The interactions of human Sex steroid binding protein (SBP) and the lignans [Nordihydrogaiaretic acid (NDGA) enterolactone (Ent), enterodiol (End)] and isoflavonoid phytoestrogens [Equol (Eq), diazein Dad), genistein (Gen)] were studied. The phytoestrogens had different dose-dependent inhibitory effects on steroid binding by SBP. Their relative efficiencies were: Ent> or = NDGA = Eq > Gen for displacing E2 and Eq > Ent > NDGA > Gen for displacing T.

Monolayer and aggregate cultures of rainbow trout hepatocytes: long-term and stable liver-specific expression in aggregates.

An aggregate culture system for rainbow trout hepatocytes was developed to study liver-specific mRNA expression. Maintenance of differentiated functions and morphology of hepatocytes were examined using both monolayer and aggregate systems. The rainbow trout estrogen receptor and vitellogenin genes were induced by estradiol and their mRNAs used as markers of cell differentiation during cell culture.