The effects of subchronic exposure to ciprofloxacin on zebrafish (Danio rerio).

OBJECTIVES: The aim of this study was to assess the impact of ciprofloxacin in Danio rerio on growth, on the development of histopathological changes in selected organs (gills, kidney, liver), and on the activity of some oxidative stress markers during a 28-day toxicity test. METHODS: Juvenile growth tests were performed on D. rerio according to OECD guideline No. 215. Fish at the age of 30 days were exposed for 28 days to a range of concentrations of ciprofloxacin (0.7 µg x L(-1)--environmental concentration, 100, 650, 1100 and 3 000 µg x L(-1)). RESULTS: There were no significant differences between the specific growth rates of fish from the test groups and from the control group. Histopathological examination revealed no pathological changes in organs of fish exposed to any ciprofloxacin concentration. The activity of glutathione S-transferase increased at the ciprofloxacin concentrations of 0.7 and 100 µg x L(-1) compared to the control. A significant decrease in glutathione reductase activity was obtained in fish exposed to ciprofloxacin at 1100 and 3000 µg x L(-1); a significant decrease in glutathione peroxidase activity was also found, but at all tested concentrations except for 100 µg x L(-1). A decrease in the concentration of thiobarbituric acid reactive substances was noted only at 100 µg x L(-1) compared to the control. CONCLUSIONS: According to our results, all tested concentrations of ciprofloxacin, including the environmental concentration, had an influence on oxidative stress markers and detoxifying enzymes in exposed fish, but did not affect fish growth or cause the development of histopathological changes in the fish organism.

Total mercury content in canine hair before and after administration of vaccines containing thiomersal.

OBJECTIVES: Thiomersal is ethylmercury containing compound. It has been used as a preservative in vaccines since the 1930s because it is very effective in preventing bacterial contamination. Ethylmercury penetrates into growing hair in a similar manner as methylmercury. DESIGN: A total of 48 hair samples were collected from vaccinated dogs. Each sample was accompanied with a questionnaire including data on age, gender, vaccinations. Total mercury content in hair, granules and vaccines was determined by the direct method of cold vapours using an AMA 254 (advance mercury analyser; Altec Ltd., Czech Republic). RESULTS: At first we performed two pre-experiments. In first pre-experiment, the highest value of total mercury content was 0.732 mg.kg-1. The content of total mercury ranged from 0.022 to 0.092 mg.kg-1 in the second pre-experiment. The results were not statistically significant in the pre-experiments. In the main experiment the lowest concentration of total mercury in dog's hair was 0.002 mg.kg-1 and the highest value was 0.560 mg.kg-1. The median value of total mercury ranged from 0.023 to 0.033 mg.kg-1. The results were not statistically significant in the main experiment. Total mercury content in vaccines corresponded with the declared quantity. Rather, results showed mercury content to be correlated with the consumption of feed containing fish. CONCLUSIONS: Thiomersal preservative, contained in vaccine, does not increase content of total mercury in canine hair. Our results have shown that content of mercury in hair depends on fish consumption (fish granules, fish treats and fresh fish).

Biochemical markers for the assessment of pollution of selected small streams in the Czech Republic.

OBJECTIVES: The objective of the presented study was to investigate levels of the most important biochemical markers in fish which were caught upstream and downstream from sites near waste water treatment plants situated at 3 selected small streams of the Czech Republic. Organic pollutants and mercury were determined in muscle tissue of fish for complex assessment. DESIGN: Levels of biochemical markers (cytochrome P450 (CYP450), ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), vitellogenin (VTG)) were measured in selected tissues (liver, plasma, brain, gill and kidney) samples of brown trout. The concentrations of persistent organic pollutants (POPs) and mercury were determined in muscle samples. RESULTS: Significantly higher levels of biochemical markers (EROD, GST, VTG) were measured downstream from waste water treatment plant (WWTP) in Vlachovo Brezí (the small Libotýnský brook). Values of biochemical markers at the other localities Cerný brook and Moravice River were measured downstream from WWTP consistently or slightly lower with values of upstream. The values of POPs and mercury were in all monitored sites higher upstream compared with downstream from WWTP. The highest values of POPs and mercury were found on Cerný brook in Bruntál (more industrial and agricultural activity). CONCLUSION: The highest occurrence of selected POPs and mercury was generally upstream suggesting that small WWTP are able to partially remove these substances in those locations. But finding higher values of biochemical markers in downstream shows that there are many other substances endocrine disrupting chemicals (EDCs) that WWTP are unable to remove.

Oxidative stress parameters in fish after subchronic exposure to acetylsalicylic acid.

OBJECTIVES: The aim of this study was to investigate the effects of subchronic exposure of juvenile development stages of zebrafish (Danio rerio) to acetylsalicylic acid using selected oxidative stress biomarkers. DESIGN: Toxicity test with acetylsalicylic acid was performed according to the OECD Guideline No. 215, fish D. rerio aged 30 days were used. The tested concentrations were 0.004, 0.4, 40, 120 and 250 mg.L-1, duration of the test was 28 days. Products of lipid peroxidation and antioxidant enzymes were determined as the markers of oxidative stress. RESULTS: Significantly increased glutathione S-transferase activity was found in fish exposed to acetylsalicylic acid concentrations 40, 120 and 250 mg.L-1. The highest values of glutathione reductase activity were found in the groups exposed to acetylsalicylic acid concentrations 0.4, 40 and 120 mg.L-1. In the group exposed to acetylsalicylic acid concentrations 40 mg.L-1, catalase activity was significantly higher compared to the control group. Significantly higher glutathione peroxidase activity was found in the groups exposed to acetylsalicylic acid concentrations 0.004 and 120 mg.L-1. The concentrations of TBARS were lower in fish exposed to acetylsalicylic acid at all tested concentrations compared to control. CONCLUSION: The subchronic exposure of zebrafish to acetylsalicylic acid causes an increase in activity of antioxidant and biotransformation enzymes and a decrease in lipid peroxidation.

Acute toxicity of acetylsalicylic acid to juvenile and embryonic stages of Danio rerio.

OBJECTIVES: The aim of this study was to compare the acute toxicity of acetylsalicylic acid to embryonic and juvenile stages of aquarium fish - zebrafish (Danio rerio), oxidative stress parameters and detoxifying enzyme. METHODS: Tests were performed according to OECD No. 203 (Fish, acute toxicity test) and OECD No. 212 (Fish, short-term toxicity test on embryo and sac-fry stages) methodology. RESULTS: The results showed the mean acetylsalicylic acid LC50 value to be 567.7 mg/L in juvenile zebrafish. The acute toxicity of acetylsalicylic acid for zebrafish embryos was 274.6 mg/L. Statistically significantly higher activity of GST was found in concentrations 340, 380 and 420 mg/L of acetylsalicylic acid. TBARS, GPx and GST didn't show statistically significant activity in tested concentrations of acetylsalicylic acid. CONCLUSIONS: The results revealed a statistically significantly higher degree of sensitivity in the embryonic stages of zebrafish compared to its juveniles. Acetylsalicylic acid did not cause statistically significantly higher antioxidative defence in zebrafish.

Effects of cyhalothrin-based pesticide on early life stages of common carp (Cyprinus carpio L.).

The effects of Nexide (a.i. gamma-cyhalothrin 60 g L(-1)) on cumulative mortality, growth indices, and ontogenetic development of embryos and larvae of common carp (Cyprinus carpio L.) were studied. Levels of oxidative stress parameters glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation were determined. Eggs of newly fertilised common carp were exposed to Nexide at concentrations 5, 25, 50, 100, and 250 µ g L(-1) (0.3, 1.5, 3, 6, and 15 µ g L(-1) gamma-cyhalothrin). All organisms exposed to concentrations higher than 50 µ g L(-1) died soon after hatching; at 25 µ g L(-1), 95% mortality was recorded. Larvae exposed to 5 µ g L(-1) showed significantly lower growth and retarded ontogenetic development compared to control. Histological examination of the livers of larvae from the exposed group revealed dystrophic changes. The value of detoxification enzyme GST of organisms from the exposed group was significantly higher compared to the control and the value of defensive enzyme GPx was significantly lower compared to the control. The results of our investigation confirmed that contamination of aquatic environment by pesticides containing cyhalothrin may impair growth and development of early life stages of carp and cause disbalance of defensive enzymes.

The effect of mycotoxin deoxynivalenol on haematological and biochemical indicators and histopathological changes in rainbow trout (Oncorhynchus mykiss).

Deoxynivalenol (DON), produced by the Fusarium genus, is a major contaminant of cereal grains used in the production of fish feed. The effect of mycotoxin deoxynivalenol on rainbow trout (Oncorhynchus mykiss) was studied using a commercial feed with the addition of DON in a dose of 2 mg/kg feed. The fish (n=40) were exposed to the mycotoxin for 23 days. The trout were divided into two groups, control and experimental groups. Control groups were fed a commercial feed naturally contaminated with a low concentration of DON (225 µg/kg feed); experimental groups were fed a commercial feed with the addition of DON (1964 µg/kg feed). Plasma biochemical and haematological indices, biometric parameters, and histopathological changes were assessed at the end of the experiment. The experimental groups showed significantly lower values in MCH (P<0.05). In biochemical indices, after 23-day exposure, a significant decrease in glucose, cholesterol (P<0.05), and ammonia (P<0.01) was recorded in the experimental group compared to the control group. Our assessment showed no significant changes in biometric parameters. The histopathological examination revealed disorders in the caudal kidney of the exposed fish. The obtained data show the sensitivity of rainbow trout (O. mykiss) to deoxynivalenol.

Evaluation of biochemical, haematological, and histopathological responses and recovery ability of common carp (Cyprinus carpio L.) after acute exposure to atrazine herbicide.

The aim of study was to evaluate the effect of atrazine exposure (5, 15, 20, and 30 mg·L(-1)) on common carp and the ability of regeneration. During 96 h exposure we observed abnormal behavior in fish exposed to 20 and 30 mg·L(-1). Mortality and histological alterations were noticed only in the group exposed to 30 mg·L(-1). Most experimental groups showed significantly (P < 0.05) lower values of haemoglobin, haematocrit, leukocyte, and lymphocyte and significantly higher values of monocytes, segmented and band neutrophile granulocytes, and also metamyelocytes and myelocytes. A significantly lower (P < 0.05) leukocyte count was also recorded in experimental groups (5 and 15 mg·L(-1)) after recovery period. Statistically significant (P < 0.05) alterations in glucose, total protein, lactate, phosphorus, calcium, and biopterin as well as in activities of ALT, AST, ALP, and LDH were found in most experimental groups. These changes were most apparent in the groups exposed to 20 and 30 mg·L(-1). Most of the indices were found to be restored after the 7-day recovery period with the exception of LDH, ALT, and lactate in the group exposed to 15 mg·L(-1). Our results showed that atrazine exposure had a profound negative influence on selected indices and also on histological changes of common carp.