Developmental expression and estrogen responses of endocrine genes in juvenile yellow perch (Perca flavescens).

The present study examines the expression of growth-regulating genes (gh, prl, smtl and igf1b), the estrogen receptors (esr1 and esr2a) and aromatase (cyp19a1a) in developing yellow perch. To gain an initial understanding into the endocrine control of growth preceding and involved with sexual size dimorphism (SSD), where females have been reported to grow faster and larger than males, young of the year fish were sampled for length, weight and tissues at several time points (102-421 days post-hatch (dph)). Positive growth was seen in both sexes over the sampling interval, but SSD was not manifested.

Effects of xenobiotics and steroids on renal and hepatic estrogen metabolism in lake trout.

Experiments were conducted to (1) elucidate the biochemical pathways of E2 metabolism in the lake trout (Salvelinus namaycush) kidney and liver, and (2) test the hypothesis that specific xenobiotics and endogenous steroids inhibit E2 metabolism by these tissues. Kidney and liver tissue fragments from immature lake trout were incubated in vitro in the presence of radiolabelled E2 plus various xenobiotics or steroids. E2 metabolites were identified by liquid chromatography/mass spectroscopy, and quantified by liquid scintillation spectroscopy.

Influence of dietary genistein levels on tissue genistein deposition and on the physical, chemical, and sensory quality of rainbow trout, Oncorhynchus mykiss.

Genistein, the primary isoflavone in soybean, is one of the chemical components responsible for some of the off-flavors associated with soy-based foods. The potential effects of genistein on the sensory and chemical quality of fish muscle may affect the full utilization of soybean meal as an alternative protein in aquaculture diets. Fingerling trout fed commercial diets containing 0, 500, 1000, or 3000 ppm pure genistein were analyzed after 6 and 12 months of feeding.