Potential ecotoxicity of substrate-enriched zinc oxide nanoparticles to Physalaemus cuvieri tadpoles.

Although the ecotoxicological effects of ZnO nanoparticles (ZnO NPs) have already been reported in different taxa, little is known about their impacts on amphibians. Thus, we aimed to evaluate the potential effects of exposure of Physalaemus cuvieri tadpoles to substrates enriched with ZnO NPs (and with its ionic counterpart, Zn+2, ZnCl2 - both at 100 mg/kg) previously used in the cultivation of Panicum maximum (Guinea grass). We showed that although exposure for 21 days did not impact the survival, growth, and development of tadpoles, we noted an increase in the frequency of erythrocyte nuclear abnormalities in the "ZnCl2" and "ZnONP" groups, which was associated with suppression of antioxidant activity in the animals (inferred by SOD and CAT activity and DPPH free radical scavenging capacity). In the tadpoles of the "ZnONP" group, we also noticed a reduction in creatinine and bilirubin levels, alpha-amylase activity, and an increase in alkaline phosphatase activity. But the treatments did not alter the activity of the enzymes lactate dehydrogenase and gamma-glutamyl-transferase and total protein and carbohydrate levels. On the other hand, we report a cholinesterase and hypotriglyceridemic effect in the "ZnCl2" and "ZnONP" groups. Zn bioaccumulation in animals, from ZnO NPs, from Zn+2 released from them, or both, has been associated with causing these changes. Finally, principal component analysis (PCA) and the values of the "Integrated Biomarker Response" index revealed that the exposure of animals to substrates enriched with ZnO NPs caused more pronounced effects than those attributed to its ionic counterpart. Therefore, our study reinforces the need to consider the environmental risks of using these nanomaterials for agricultural purposes for amphibians.

An insight on the mutagenicity and cytotoxicity of zinc oxide nanoparticles in Gallus gallus domesticus (Phasianidae).

Although the toxicity of zinc oxide (ZnO) nanoparticles (NPs) is known in several experimental models, little is known about their effects on bird representatives. Therefore, the aim of the current study is to evaluate the mutagenic and cytotoxic potential of ZnO NPs in chicks belonging to species Gallus gallus domesticus, as well as to analyze the role played by nuclear and erythrocyte morphological changes as biomarkers of the toxicity of these nanopollutants. Two doses of ZnO NPs (0.245 mg k-1 and 245.26 mg kg-1) were herein tested; they were determined based on the predictive environmental concentration of these NPs (760 µg L-1), on the body biomass of the analyzed animals and on the mean daily water intake/bird. Birds were subjected to two intraperitoneal applications (one per day) of solution containing ZnO NPs; they were euthanized 48 h after the first application. The herein collected data have shown that NPs were capable of inducing the formation of different types of erythrocyte nuclear abnormalities, such as micronucleus, binucleate erythrocytes, blebbed, reniform and multilobulated nuclei, as well as symmetric and asymmetric constriction. In addition, changes in the size and shape of erythrocytes were observed in birds exposed to ZnO NPs. Zn bioaccumulation analysis conducted in brain tissues confirmed the association between these changes and animal exposure to ZnO NPs. Thus, besides confirming the toxicological potential of ZnO NPs, to the best of our knowledge, the current study is the first report on the mutagenic and cytotoxic effects of these NPs on bird representatives.

Evaluating the reproductive toxicology of tannery effluent in male SWISS mice.

The transformation of skin in-natura into leather in tannery industries generates large volumes of organic matter that attract small mammals. i.e., rodents living close to these facilities. Animals foraging in the backyards of such industries get exposed to the effluent produced by them; however, attention has not been given to the impacts of such exposure on the reproductive biology of these animals. Thus, our study assessed whether the direct exposure to this effluent for periods longer than 90 days leads to reproductive loss in male Swiss mice. We assessed animals' sexual behavior at the end of the experimental period and analyzed their testicular histology, as well as semen quality and volume, besides measuring pro-inflammatory markers and assessing the reproductive performance of the exposed animals. Based on the herein collected data, mice exposed to the gross effluent collected in the backyard of a tannery industry, as well as to the effluent diluted in 5% of water, presented behavioral and histological changes in the testes, disorganized germinal cells in the seminiferous tubules and inflammatory process in intertubular spaces. The inflammatory process resulted from increased proinflammatory cytokine (IFN-gamma and CCL2) concentrations in the testes, fact that explained the larger number of sperm abnormalities and the reduced number of produced sperms. These factors, along with the previously reported changes, may have led to the low reproductive performance of animals exposed to the tested pollutant, which was assessed through the lethal dominant test. This pioneering article addressed the reproductive impact caused by the direct exposure of small rodents to tannery effluents. The research helped better understanding how these pollutants can influence natural ecosystems.

The potential reproductive toxicity of tannery effluent to the estrous cycle and ovarian follicular dynamics of female Swiss mice.

Although the toxic effects of tannery effluent (TE) on tanning-industry workers have been reported in many studies, its effects on females' reproductive system are unknown. We aimed at evaluating the effects of direct contact with TE on the "emotional" status, estrous cycle (during 15 consecutive exposure days), and ovarian follicular dynamics of female Swiss mice at the end of the experiment to broaden the knowledge about the toxicity of this pollutant. The herein adopted exposure protocol simulated tanning-industry workers' exposure to TE. The test animals were subjected to 45 exposure days, for 1 h a day, 5 days a week (from Monday to Friday). Based on the collected data, female mice exposed to TE recorded high anxiety index in the elevated plus maze test, although we did not observe changes in their estrous cycle. The smaller total and specific number of ovarian follicles (types 1 to 6) and the higher frequency of degenerating follicles (atresic) in female mice exposed to TE marked the folliculogenesis reduction in them. Therefore, our study was the first to provide evidences that the exposure to TE can cause reproduction issues in female mice, as well as the first experimental insight about the impact of unhealthy work activities in tanning industries on women's reproductive system.

Mutagenic assessment of Lithobates catesbeianus tadpoles exposed to the 2,4-D herbicide in a simulated realistic scenario.

The aim of the current study is to assess possible erythrocyte mutagenic effects on Lithobates catesbeianus tadpoles exposed to water contaminated with 2,4-D. In order to do so, tadpoles were exposed to a predictive and environmentally relevant herbicide concentration (1.97 mg/L), which is likely to be found in lentic environments formed by superficial water runoffs in pasture areas where the herbicide was applied. The micronucleus test, as well as tests for other nuclear abnormalities, was conducted after 3, 5, and 9 days of exposure (d.e.). Changes in the biomass and mouth-cloaca length or interference in the larval development of the animals (in the three evaluated times) were not recorded. However, tadpoles exposed to 2,4-D showed the highest total number of nuclear abnormalities, as well as the highest frequency of binucleated erythrocytes and kidney-shaped nuclei (shortly after 3 d.e.). The micronucleus frequency was also higher in animals exposed to 2,4-D (in the 3rd, 5th, and 9th d.e.), as well as the frequency of binucleated cells (3rd, 5th, and 9th d.e.) presenting notched (9th d.e.) and blebbled (9th d.e.) nuclei in comparison to those of the control, after 5 and 9 days of exposure. Therefore, the current study is a pioneer in showing that 2,4-D has a mutagenic effect on L. catesbeianus tadpoles, even at low concentrations (environmentally relevant) and for a short period of time, a fact that may lead to direct losses in anuran populations living in areas adjacent to those subjected to 2,4-D herbicide application.

Correction to: Histological liver chances in Swiss mice caused by tannery effluent.

There is a problem in the original publication of this paper (Figure 2 Graphs are in Portuguese). Shown in this paper is the correct version.

Histological liver chances in Swiss mice caused by tannery effluent.

Although tannery effluents are known for being highly toxic to organisms, reports about the effects of the intake of these xenobiotics on experimental mammal models are recent. Studies about the damages the chronic intake of these effluents can cause in the liver of outbred mice remain an unexplored field. Thus, the aim of the present study is to assess (histological) the hepatic condition of Swiss mice (outbred strain) chronically exposed to the intake of different raw tannery effluent concentrations diluted in water for 150 days. Accordingly, the mice (males and females) were divided in the following groups: control group-animals treated with drinking water, only; and groups 5 and 10%-treated with raw tannery effluent diluted in water. After exposure, the animals were subjected to euthanasia for liver fragment sample collection and histological analysis, respectively. Moderate hydropic degeneration was observed in the centrilobular regions of the liver of mice exposed to 5 and 10% tannery effluent, as well as greater amounts of hepatocytes presenting karyomegaly and necrotic hepatocytes, and a smaller amount of Kuffer cells in the liver of mice exposed to the xenobiotic. Finally, animals exposed to 10% tannery effluent showed mild hyperplasia of the bile ducts in the portal areas and fibroblast proliferation around the bile ducts, thus suggesting a fibrous process. Except for the frequency of hepatocytes presenting karyomegaly (lower in females), the herein observed hepatic changes were similar in male and female Swiss mice. Accordingly, the present data support the hypothesis that the chronic intake of tannery effluent by outbred mice (Swiss) causes damages in the liver, a fact that broadens the knowledge about the toxic potential of this pollutant, which goes beyond that of C57Bl/6J male mice (inbred strain).

Memory and depressive effect on male and female Swiss mice exposed to tannery effluent.

Although tannery industries generate substantial profits to the countries they are located in, they work with one of the most environmentally harmful human activities. Tannery effluents (TE) are highly toxic; thus, their improper release into water bodies may cause severe problems to individuals depending on this water. Therefore, the aim of the current study is to assess the effects of oral exposure to TE on the anxiety-, memory deficit- and depression-predictive behaviors in male and female Swiss adult mice. The following experimental groups were set in order to do so, control, positive control (reference drugs) and effluent. The animals in the effluent group were treated with 5% TE diluted in potable water for 15 consecutive days. The neurobehavioral tests started on the 12th experimental day. The results found through the elevated plus-maze test (for anxiety prediction) showed no anxiogenic or anxiolytic effects on animals exposed to TE. On the other hand, animals treated with TE showed short- and long-term memory deficit in the object recognition test, as well as depression-predictive behavior in the forced swimming test. These results may concern the high concentration of heavy metals and neurotoxic organic compounds in the TE. Therefore, the oral exposure to TE, even for a short period-of-time, has effects on the central nervous system (CNS) that lead to neurobehavioral changes. Thus, the current study broadens the knowledge on this research field by demonstrating the neurotoxicity of xenobiotics to male and female Swiss mice.

Anxiety and memory deficits induced by tannery effluent in C57BL/6J female mice.

This study aimed to evaluate the behavior of female C57Bl/6J mice exposed to tannery effluents diluted in drinking water. Female mice were divided into a control group, in which the animals received only drinking water, and experimental groups, which received raw tannery effluent in 7.5 and 15 % concentrations diluted in water (period of 60 days). In the last experimental week, the mice (in diestrus phase) were subjected to different behavioral tests: elevated plus-maze, open-field test, forced swim test, and object recognition test. Our data demonstrated that exposure to tannery effluent increased the anxiety index of animals and decreased the locomotion ratio in the central quadrants/total, indicating an increase in anxiety-like behavior. Regarding the forced swim test, we did not observe changes in the evaluated behaviors. There were no statistically significant differences in the recognition index of the novel and familiar object in the groups exposed to tannery effluent compared with the control group, indicating a possible influence of the constituents of tannery effluent on cognition. Thus, our findings support the hypothesis that effluents, containing neurotoxic substances, could cause behavioral disruptions in female C57Bl/6J mice.