Erythromycin in the aquatic environment: deleterious effects on the initial development of zebrafish.

Due to the large volume of erythromycin continuously reaching waterbodies and its high persistence, this antibiotic drug has been detected in the aquatic environment at elevated concentrations. Although the problem of the presence of erythromycin in the environment is evident due to its influence in development of antimicrobial resistance, the toxicological consequences on non-target organisms remain to be determined. There are no apparent data on the impact of environmentally relevant concentrations of erythromycin on developing fish. Data on toxic effects during development are essential for evaluation of environmental risk to organisms. Therefore, the aim of this study was to investigate the effects of exposure to erythromycin on certain parameters including hatchability, survival rate, heart rate, and behavior in developing zebrafish. Zebrafish were exposed to a range of environmentally relevant concentrations of antibiotic (0.001, 0.01, 0.1, 1 µg/L) and one concentration 10-fold higher (10 µg/L). Exposure to erythromycin at 0.1 µg/L delayed hatching and decreased survival rate. Exposure to all tested concentrations increased heart rate. Further, exposure to erythromycin at 1 or 10 µg/L enhanced swimming activity. Our results indicated that erythromycin present in the aquatic environment might lead to disabling consequences in developing fish organisms and subsequently may result in ecological imbalance in the natural environment.

Oxidative state of the frugivorous bat Sturnira lilium (Chiroptera: Phyllostomidae) in agricultural and urban areas of southern Brazil.

Exposure to contaminants is one of the main threats to all living organisms. In this context, bats have been used to indicate environmental contaminants in urban and agricultural environments, since they are extremely sensitive to changes in the ecosystem and easily accumulate waste in their body tissues. Among bats, Sturnira lilium, is a frugivorous species widely distributed and abundant in Brazil that uses an extensive variety of habitats and shelters. In this study, we aimed to evaluate the oxidative state of S. lilium individuals in agricultural and urban areas in southern Brazil. Individuals were sampled in agricultural and urban areas from November 2017 to March 2018 through the mist-net method. Parameters of the superoxide dismutase (SOD) and catalase (CAT) enzyme activity, non-protein thiols (NPSH), and lipid peroxidation (TBARS) were determined based on liver tissue. A total of 46 individuals were captured, 29 of them in urban areas and 17 in agricultural areas. We found that S. lilium individuals from agricultural areas showed a significant increase in TBARS, NPSH, and SOD activity, compared to individuals from urban areas. The activity of the antioxidant enzyme CAT did not differ. The present findings suggest that the species S. lilium, which are widely distributed and abundant in Brazil in urban and agricultural areas, can usefully be employed in biomonitoring programs. Further studies are to be encouraged to refine our knowledge on the potential DNA damage caused by environmental contamination, as well as identify potential contaminants to bats.

Exposure to the herbicide 2,4-dichlorophenoxyacetic acid impairs mitochondrial function, oxidative status, and behavior in adult zebrafish.

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most commonly used herbicides worldwide. While the effects of 2,4-D in target organisms are well known, its consequences in nontarget organisms are not fully explained. Therefore, the purpose of this study was to investigate the effects of the herbicide on mitochondrial energy metabolism, oxidative status, and exploratory behavior in adult zebrafish. Animal exposure to 2,4-D increased cytochrome c oxidase and catalase activities and reduced SOD/CAT ratio, moreover, increased the total distance traveled and the number of crossings. Finally, animals exposed to 2,4-D spent more time in the upper zone of the tank and traveled a long distance in the upper zone. Overall, our results indicate the 2,4-D can provoke disabling effects in nontarget organisms. The obtained data showed that exposure to 2,4-D at environmentally relevant concentrations alters mitochondrial metabolism and antioxidant status and disturbs the zebrafish innate behavior.