Initial Hormone Concentration Research Articles

Anaerobic Transformation Kinetics and Mechanism of Steroid Estrogenic Hormones in Dairy Lagoon Water

Wastewater from concentrated animal feeding operations (CAFOs) frequently contains high concentrations of steroid estrogenic hormones. Release of these hormones into the environment may occur when CAFO wastewater is applied to agricultural lands as a nutrient and water source for crop production. To assess the potential risk of hormone contaminants derived from animal wastewater, we investigated the transformation kinetics and mechanisms of three natural estrogenic hormones (17α-estradiol, 17β-estradiol, and estrone) in aqueous solutions blended with dairy lagoon water under anaerobic conditions. Initial transformations of the three hormones in the dairy lagoon water were dominated by biodegradation and the degradation rates were temperature-dependent. The total amounts of hormones (initial concentration at 5 mg L(-1)) remaining in the solution after 52 days at 35 °C accounted for approximately 85%, 78%, and 77% of the initial amounts of 17α-estradiol, 17β-estradiol, and estrone, respectively. This observation suggests that these hormones are relatively stable over time and may accumulate in anaerobic or anoxic environments and anaerobic CAFO lagoons. A racemization reaction between 17α-estradiol and 17β-estradiol via estrone was observed in aqueous solutions in the presence of CAFO wastewater under anaerobic conditions. The initial hormone concentrations did not affect this degradation mechanism. A reversible reaction kinetic model was applied to fit the observed transformation dynamics. The degradation and regeneration of the parent hormone and its metabolites were successfully simulated by this model. The information in this study is useful for assessing the environmental risk of steroid hormones released from CAFO wastewater and to better understand why these hormone contaminants persist in many aquatic environments.

Impact of Feed Storage Conditions on Growth and Efficacy of Sex Reversal of Nile Tilapia

Effects of storage temperature (ambient or refrigerated) and storage time on hormone-treated feed and the effectiveness of various feeds to reverse the sex of fry of Nile tilapia Oreochromis niloticus were studied. Seven feed storage regimes were tested, and fry were fed feed treated with 17α-methyltestosterone (MT) or a nontreated feed for 28 d. There was no significant difference among the stored MT-treated diets and ability to sex-reverse fry (P > 0.05). All treatments yielded 99–100% males. There were no significant differences in fry growth, survival, or feed conversion ratio (P > 0.05) among stored diets. Hormone analysis of feed showed that the initial concentration of hormone in the feed was 60.4 mg MT/kg feed, decreasing to 54.8 mg MT/kg feed after being stored under refrigeration for 2 months followed by 26 d at tropical ambient temperature (28 ± 1.5°C). Lipid analysis indicated that the feed was not rancid after storage for the period and conditions just described.

Ligand-dependent regulation of the 1,25-dihydroxyvitamin D3 receptor in rat osteosarcoma cells.

The specific binding of radiolabeled 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) to intact rat osteosarcoma (ROS 17/2) cells was followed for 24 h. In the presence of 0.5-1.5 nM 1,25(OH)2D3, hormone binding increased over a period of 12 h, from 1.1 X 10(4) to 1.3 X 10(5) receptors/cell. The elevated level of hormone binding persisted through 24 h provided that the initial concentration of hormone was maintained. The concentration dependence of this increase in receptor level was centered between 10 and 30 pM 1,25(OH)2D3, and the binding at 12 h exhibited the metabolite specificity expected for a 1,25(OH)2D3 receptor. The t 1/2 values for the disappearance of unoccupied and occupied receptors were roughly the same, approximately 2.7 h; therefore, the increase in hormone binding was not due to receptor stabilization. In comparison, hormone-receptor complexes appeared to dissociate with a t 1/2 of 1 h. alpha-Amanitin treatment reduced the magnitude of receptor accumulation by 50-60%, indicating that mRNA synthesis was required to achieve the maximal response. Ligand-dependent regulation of cellular receptor levels provides a mechanism for amplifying the primary hormonal signal and is predicted to influence the kinetics, magnitude, and dose dependence of cellular responses.