Search

Abstract Mercury is one of the important pollutants of the environment. Therefore, it’s necessary to monitor quantity of mercury especially in aquatic ecosystems. The main goal of the presented study was to compare the content of total mercury in tissues of fish coming from the Czech Republic, an important carp exporter, with focus on comparison of mercury content between 3 different ponds, its comparison between different fish species and between different tissues of the same species, and estimation whether the mercury content in tissues meets the limit given in the Commission Regulation (EC) No. 1881/2006 or not. Total mercury concentration was measured in 90 fish specimen sampled from three ponds (Velky Kocelovicky, Mysliv and Zehunsky) in autumn 2018. The values of total mercury in fish tissues was measured by atomic absorption spectrometry. The content of total mercury in the tissues decreased as follows: muscle > liver > gonads > scales. The highest average content of total mercury in muscle was 0.1517 ± 0.0176 mg/kg coming from pike caught in Velky Kocelovicky pond. In contrast, the lowest average content of total mercury in muscle 0.0036 ± 0.0003 mg/kg was found in carp tissue coming from the locality of Zehunsky pond. We confirmed that the predatory fish are more exposed to mercury than non-predatory fish. None of the monitored localities exceeded the set regulatory limit. Thus, our study shows that fish coming from these ponds are safe in terms of total mercury content.

The aim of our study was to investigate the intracellular toxicity mechanisms of the photoactive, potentially anti-cyanobacterial agent hydrogen peroxide (H2O2) in Microcystis aeruginosa, which represents one of the most significant toxin-producing cyanobacterial species in European water bodies. Metabolic activity and cell membrane integrity were evaluated by flow cytometry in cyanobacteria exposed to H2O2 in the dark or light; the relationships between exposure effects and the kinetics of hydrogen peroxide decomposition were studied. In the light (irradiance 140 µmol m−2 s−1), cyanobacteria were exposed to initial H2O2 concentrations of 0.00 (control), 0.75, 2.00, and 4.00 mg l−1 respectively, while in the dark concentrations were ten times higher. Flow cytometry and chlorophyll a fluorescence measurements suggested that hydrogen peroxide exposure elicits an immediate decline of metabolic (esterase) activity, measured as a decrease in fluorescein fluorescence after hydrolysis of fluorescein diacetate (FDA), and immediate changes of chlorophyll a fluorescence parameters, followed later by an increase in the percentage of membrane-compromised (SYTOX Green positive) cells. When the concentration of H2O2 used was lethal (in the two highly exposed treatments in the light), a significant drop in total cell counts was detected, whereas in other treatments no drop was observed during the entire experimental period (72 h). Our study also confirmed that light is one of the critical factors affecting H2O2 decomposition and thus greatly influences its toxicity. Whereas in the light, M. aeruginosa exposed to 0.75 mg l−1 H2O2 recovered after all the H2O2 had decomposed, in the dark H2O2 decomposed relatively slowly and its toxic effects on the cyanobacteria were observed over the whole 72-h period, though without cell lysis in any experimental concentration. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate subchronic toxic effects of the preparation LASSO MTX (alachlor 42% W/V) on hematological indices and histology of the common carp ( Cyprinus carpio L.). In carp exposed for 28 days to LASSO MTX in the concentration of 2,400 μg L−1, significant differences ( p < 0.05), were detected in all indices of the erythrocyte profiles tested except hematocrit (PCV) when compared to controls. At a lower exposure (240 μg L−1) concentration of blood hemoglobin and mean corpuscular hemoglobin were significantly reduced. In contrast, no influence of the preparation on leucopoiesis was demonstrated, and only slight changes were observed in histopathological indices. [ABSTRACT FROM AUTHOR]

Objectives: Effects of metribuzin on biochemical and haematological indices, induction of specific biomarkers and impacts on biometric parameters of Cyprinus carpio were investigated for subchronic conditions., Methods: Juvenile fish were exposed to 0.175 mg.L-1 or 1.75 mg.L-1 metribuzin for 28 days. Haematological indices were assessed using unified methods of haematological examination in fish. Biochemical indices were determined by biochemical analyzer, hepatic vitellogenin content was estimated by direct sandwich ELISA. Cytochrome P450 concentration and ethoxyresorufin O-deethylase activity were measured in liver spectrophotometrically and spectrofluorimetrically, respectively., Results: Increased haematocrit and RBC count were found in fish exposed to 1.75 mg.L-1 metribuzin compared to control fish (p<0.05). Other indices contents and biomarkers levels were not significantly changed by either concentration of metribuzin., Conclusion: Sublethal metribuzin pollution may have adverse impacts on haematological parameters in common carp.

Objectives: Xenoestrogenic potential of propylparaben (PP), one of the most commonly used preservatives in drugs, cosmetics and food, was investigated in vivo using zebrafish (Danio rerio)., Methods: Juvenile zebrafish (20 days post hatching) were exposed to three different concentrations of propylparaben (PP) dissolved in ethanol and added into the water. After 20 days of exposure the fish were euthanized and vitellogenin concentrations in their whole body homogenates were measured by the method of direct sandwich ELISA. Simultaneously, vitellogenin concentrations in either fish from the control group (exposed to solvent without the substance tested) and in fish from the positive control group (exposed to natural estrogen 17beta-estradiol) were measured., Results: Vitellogenin concentration in whole body homogenates of control fish was 400 (396-540) ng/ml(-1) (geometric mean (95% CI)). Zebrafish exposure to propylparaben at the concentrations of 0.1; 0.4 and 0.9 mg/l(-1) elicited statistically significant decline (P<0.001) of vitellogenin production, i.e. geometric means of vitellogenin concentrations in whole body homogenates were 240 (186-311); 218 (175-270) and 270 (234-311) ng/ml(-1), respectively. Conversely, the geometric mean of vitellogenin concentration in whole body homogenates of zebrafish exposed to 100 ng/ml(-1) of 17beta-estradiol (positive control) was significantly higher (P<0.001) than values in all other groups, i.e. 35,553 (16,860-74,968) ng/ml(-1)., Conclusions: Our results suggest an antiestrogenic potential of propylparaben tested in vivo in juvenile zebrafish (Danio rerio). The estrogenic effect of 17beta-estradiol was confirmed.