Simultaneous Measurement of Sex Steroid Hormones in Largemouth Bass (Micropterus salmoides) Plasma by Application of Liquid Chromatography–Tandem Mass Spectrometry

Sex steroid hormones are potential biomarkers of reproductive function in teleost fish, but their measurement continues to rely on antibody-based assays. The objective of this study was to optimize a robust and simultaneous liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for measurement of eight steroid hormones (cortisol, 11-ketotestosterone, estradiol, 17α-ethynyl estradiol, estrone, estriol, progesterone and testosterone) in fish plasma. The extraction was followed by liquid–liquid extraction with tert-butyl methyl ether and time scheduled multi-reaction monitoring (sMRM) was used for quantitation of steroids. Validation of method performance using charcoal-stripped human plasma showed extraction recoveries for eight steroids ranged from 85.5 to 108.2% with matrix effects > 80%. The limits of quantitation were 0.01 pg/μL for testosterone, 0.05 pg/μL for cortisol and progesterone, 0.1 pg/μL for 11-ketotestosterone, estradiol and estrone, 0.125 pg/μL for estriol and 0.25 pg/μL for 17α-ethynyl estradiol. The proposed method was applied to plasma samples of largemouth bass (Micropterus salmoides) collected from contaminated (Lake Apopka) and reference sites (Wildcate Lake) in Florida. Concentrations of testosterone, cortisol, estradiol and estrone were significantly different in female fish, but plasma concentration of cortisol was only statistically different in male fish between two sites (P < 0.05). This study demonstrates the application of a robust LC–MS/MS analysis for a range of sex steroid hormones representative of endocrine function in a top predator, largemouth bass.

Morphometric comparison of the growth curve in Nile tilapia (Oreochromis niloticus) sexually reverted to masculinized and feminized

Aquaculture is an industry in development around the world that allows covering the nutritional demand with a high nutritional value. Within this industry, monosex crops of some species, such as the Nile tilapia (Oreochromis niloticus), stand out. In this study, the effect of the administration of 17α-ethinyl estradiol and 17α-methyltestosterone on the morphometry of Nile tilapia at different times was evaluated. Nile tilapia were raised under controlled conditions and divided into three groups: control: no hormone treatment; feminized: treated with 17α-ethynyl estradiol and masculinized: treated with 17α-methyltestosterone. The measurements were made at 5, 10, 15, 25, 35, 40, 50, 60 and 70 days after fertilization with the morphometric technique “truss protocol.” The data were analyzed using a general linear model of repeated measurements and analysis of variance of comparison of means. The growth curve was made using the Gompertz logistic model. The results showed that the masculinized larva presented a higher growth rate and increased daily gain of weight 2.05-2 mg compared to the controls and feminized 1.67-3 mg and 7.57-4 mg, respectively. The sexual reversion of Nile tilapia with 17 α-methyltestosterone increases the growth curve of the masculinized organism and the uniformity of the final size.

Combined Process of Ozone Oxidation and Ultrafiltration as an Effective Treatment Technology for the Removal of Endocrine-Disrupting Chemicals

Endocrine-disrupting chemicals (EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. The combined process of ozone (O3) and ultrafiltration (UF) is a promising EDC removal method. The removal efficiency of five EDCs using O3, UF and their combination were investigated and compared. The five EDCs were estrone, 17β-estradiol, estriol, 17α-ethynyl estradiol and bisphenol A, which are typically present in secondary effluent. Results showed that organic matters in secondary effluent became easier to be removed by the combined process, with ultraviolet absorbance reduction enhanced by 11%–18% or 24%–26% compared to the UF or O3 alone. The removal efficiency of EDC concentration, estrogenicity and acute ecotoxicity by the combined process was 17%–29% or 54%–92%, 19% or 73%, 40% or 60% greater, respectively, than that of the O3 or UF alone. Particularly, when EDCs were treated by the combination of O3 and UF, about 100% EDC removal efficiency was achieved. Overall, the combined application of O3 and UF offers an effective approach to control the concentration and toxicity of EDCs in secondary effluent.