Use of all-male triploid population of zebrafish (Danio rerio) for evaluation of 17α-ethinylestradiol effects.

OBJECTIVES: We tested the toxicity of ethinylestradiol, a semisynthetic estrogen used in oral contraceptives, on all-male triploid zebrafish using commercial feeds and three different doses concentrations. We aimed to determine whether ethinylestradiol peroral administration resulted in vitellogenin production and whether all-male triploid zebrafish could serve as a model species for xenoestrogen testing. METHODS: The actual concentrations of 17α-ethinylestradiol were 0.0035 (low); 0.0315 (medium) and 0.365 (high) µg/g. Positive control represented commercial feeds containing 0.0465 µg/g of ß-estradiol. The experiment lasted 8 weeks. RESULTS: Our results indicate that 17α-ethinylestradiol consumption does induce vitellogenin production in triploid zebrafish. CONCLUSIONS: The simple presence of vitellogenin is a definite symptom indicative of the potential for such changes due to the action of estrogenic substances. As such, this experiment has shown that the use of all-male triploid zebrafish populations, rather than the mixed-sex populations of other species previously used, could serve as a suitable alternative model population for controlled testing of the effects of xenoestrogens on fish.

Foodborne fluoxetine impacts the immune response in rainbow trout (Oncorhynchus mykkis).

The aim of this study was to reveal the effects of foodborne fluoxetine on morphological and condition profile, hematological profile, biochemical and oxidative stress indices on juvenile rainbow trout. The study was performed according to OECD Guideline No. 215. Fluoxetine was incorporated into Biomar 921 pellets at a dose of 0.047 mg/kg (environmental concentration), 0.577 mg/kg and 6.7 mg/kg. There was statistically significant change in hematological profile, including an increasing trend in neutrophil/lymphocyte ratio and a decreasing trend in the number of lymphocytes. Measurements of oxidative stress indicated decreased activity of the detoxifying enzyme glutathione-S-transferase in the liver and kidney. However, the measurement of GR, GPx, CAT, SOD activity, and TBARS showed no changes. Histopathological examination revealed damage to the proximal tubules of caudal kidney in exposed groups. This study confirms that fluoxetine has a significant effect on immune response.

The prediction of mercury bioavailability for common carp (Cyprinus carpio L.) using the DGT technique in the presence of chloride ions and humic acid.

The ability of the DGT technique to predict Hg2+ bioavailability for input tissues (skin, gills, and scales) of common carp in the presence of chloride ions and humic acid (HA) was evaluated. The mercury accumulation by the DGT units and input tissues of carp decreased with an increasing concentration of chloride ions (29-180 mg L-1) and HA (0-5 mg L-1). In the presence of chloride ions and HA, statistically significant correlations (Pearson's correlation coefficients 0.731-0.954) were determined between the rate of mercury accumulation by input tissues of carp and the rate of mercury accumulation by the DGT units. The laboratory experiments suggest the possibility of using the DGT technique for predicting the mercury bioaccumulation in natural aquatic ecosystems instead of commonly used input tissues of fish.

Prediction of mercury bioavailability to common carp (Cyprinus carpio L.) using the diffusive gradient in thin film technique.

The mercury bioaccumulation by common carp (Cyprinus carpio L.) tissues (gills, skin, eyes, scales, muscle, brain, kidneys, liver, and spleen) and the capability of the diffusive gradient in thin film (DGT) technique to predict bioavailability of mercury for individual carp's tissues were evaluated. Carp and DGT units were exposed to increasing concentrations of mercury (Hg2+: 0 µg L-1, 0.5 µg L-1, 1.5 µg L-1 and 3.0 µg L-1) in fish tanks for 14 days. In the uncontaminated fish group, the highest mercury concentration was determined in the muscle tissues and, in fish groups exposed to mercury, the highest mercury concentration was determined in the detoxification (kidneys) and input (gills) organs. A strong and positive correlation between the rate of mercury uptake by the DGT technique and the rate of mercury accumulation by fish tissues (gills, skin, scales, and eyes) was observed.