Do Amazon turtles exposed to environmental concentrations of the antineoplastic drug cyclophosphamide present mutagenic damages? If so, would such damages be reversible?

Micronucleus test in reptiles: Current and future perspectives

Micronucleus (MN) cell counting emerged in 1973-1975 as a valid alternative for characterizing chromosomal damage caused by different agents. It was first described in mammals, but its application was rapidly extended to other vertebrates, mainly fish. However, it was not until 28 years later that this test was implemented in studies on reptiles. Nowadays, reptiles are found to be excellent non-target species from environmental contamination exposure and MN test has become a fundamental tool for analyzing genotoxic effects induced by various xenobiotics. In this article we provide an updated review of the application of the MN test in reptile species, from an ecotoxicological perspective. Therefore, we present (I) a bibliometric analysis of the available research on genotoxic-induced MN formation in reptile species; (II) the use of reptiles as sentinel organisms in ecotoxicological studies; and (III) the strength and weakness of the application of the MN test in this group. With this review, we aim to provide a comprehensive view on the use of the MN test in ecotoxicology and to encourage further studies involving reptile species.

Metal accumulation in female green sea turtles (Chelonia mydas) from Eastern Atlantic affects their egg quality with potential implications for embryonic development

Sea turtles, with their global distribution and complex life cycle, often accumulate pollutants such as metals and metalloids due to their extended lifespan and feeding habits. However, there are limited studies exploring the impact of metal pollution on the reproductive health of female sea turtles, specifically focusing on the quality of their eggs, which has significant implications for the future generations of these charismatic animals. São Tomé Island, a crucial nesting and feeding habitat for green sea turtles, underscores the urgent need for comprehensive research in this ecologically significant area. This study aimed to investigate whether metals and metalloids in the blood of nesting female green sea turtles induce genotoxic effects in their erythrocytes and affect their egg morphometric characteristics and the composition of related compartments. Additionally, this study aimed to evaluate whether the quality of energetic reserves for embryo development (fatty acids in yolk's polar and neutral lipids) is influenced by the contamination status of their predecessors. Results revealed correlations between Cu and Hg levels and increased "lobed" erythrocytes, while As and Cu negatively influenced shell thickness. In terms of energy reserves, both polar and neutral lipid fractions contained primarily saturated and monounsaturated fatty acids, with prevalent 18:1n-9, 18:0, 16:0, 14:0, and 12:0 fatty acids in yolk samples. The yolk polar fraction was more susceptible to contaminant levels in female sea turtles, showing consistent negative correlations between pollution load index and essential n3 fatty acids, including linolenic, eicosatrienoic, eicosapentaenoic, and docosapentaenoic acids, crucial for embryonic development. These metals accumulation, coupled with the reduced availability of these key fatty acids, may disrupt the eicosanoid and other important pathways, affecting reproductive development. This study reveals a negative correlation between metal contamination in female sea turtles' blood and egg lipid reserves, raising concerns about embryonic development and the species' future generations.

Hematological and genotoxic biomarkers in a natural population of freshwater turtles Trachemys dorbigni (Duméril & Bibron, 1835) (Testudines: Emydidae) living in an urban area in Southern Brazil

The present study aimed to report the morphometric and hematological indices and genotoxicity of a free-life population of D'Orbigny's slider turtles (Trachemys dorbigni) living in an urban area in Southern Brazil. For that, 16 specimens were randomly captured in an urban canal that receives irregular releases of wastewater. Biometrics and external visual changes were analyzed, such as turtle shell deformities, and the presence of parasites. Blood samples were collected to evaluate the hematological profile and the presence of micronuclei and other erythrocyte nuclear abnormalities as potential mutagenic and genotoxic effects. Water physicochemical parameters were also measured. Organisms with ectoparasites (31.25%) and small carapace deformations (56.25%) were observed, but maximum carapace length and weight were considered normal for the species according to the literature. The blood profile indicated low hemoglobin and hematocrit and a high number of total leukocytes, particularly eosinophils which characterize parasitic infections. A frequency of 0.12% for the micronucleus was considered basal, but the frequency of other erythrocyte abnormalities was evident, mainly of blebbed nuclei (63.79%), indicating chromosomal damage in the early stage. The results of this study suggest that natural populations of chelonian inhabiting urbanized areas are impacted by anthropogenic activities in the surrounding environment. Furthermore, it provides comprehensive data which can serve as a comparative model for environmental monitoring studies involving turtles.

Do Pharmaceuticals in the Environment Pose a Risk to Wildlife?

The vast majority of knowledge related to the question "To what extent do pharmaceuticals in the environment pose a risk to wildlife?" stems from the Asian vulture crisis (>99% decline of some species of Old World vultures on the Indian subcontinent related to the veterinary use of the nonsteroidal anti-inflammatory drug [NSAID] diclofenac). The hazard of diclofenac and other NSAIDs (carprofen, flunixin, ketoprofen, nimesulide, phenylbutazone) to vultures and other avian species has since been demonstrated; indeed, only meloxicam and tolfenamic acid have been found to be vulture-safe. Since diclofenac was approved for veterinary use in Spain and Italy in 2013 (home to ~95% of vultures in Europe), the risk of NSAIDs to vultures in these countries has become one of the principal concerns related to pharmaceuticals and wildlife. Many of the other bodies of work on pharmaceutical exposure, hazard and risk to wildlife also relate to adverse effects in birds (e.g., poisoning of scavenging birds in North America and Europe from animal carcasses containing pentobarbital, secondary and even tertiary poisoning of birds exposed to pesticides used in veterinary medicine as cattle dips, migratory birds as a vector for the transfer of antimicrobial and antifungal resistance). Although there is some research related to endocrine disruption in reptiles and potential exposure of aerial insectivores, there remain numerous knowledge gaps for risk posed by pharmaceuticals to amphibians, reptiles, and mammals. Developing noninvasive sampling techniques and new approach methodologies (e.g., genomic, in vitro, in silico, in ovo) is important if we are to bridge the current knowledge gaps without extensive vertebrate testing. Environ Toxicol Chem 2024;43:595-610. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Mutagenicity, hepatotoxicity, and neurotoxicity of glyphosate and fipronil commercial formulations in Amazon turtles neonates (Podocnemis expansa)

Pesticides are considered one of the main causes of the population decline of reptiles worldwide, with freshwater turtles being particularly susceptible to aquatic contamination. In this context, we investigated the potential mutagenic, hepatotoxic, and neurotoxic effects in neonates of Podocnemis expansa exposed to substrate contaminated with different concentrations of glyphosate and/or fipronil during embryonic development. Eggs collected from the natural environment were artificially incubated in sand moistened with pure water, water added with glyphosate Atar 48® at concentrations of 65 and 6500 μg/L (groups G1 and G2, respectively), water added with fipronil Regent® 800WG at 4 and 400 μg/L (groups F1 and F2, respectively) and, water added with the combination of 65 μg/L glyphosate and 4 μg/L fipronil or with 6500 μg/L glyphosate and 400 μg/L fipronil (groups GF1 and GF2, respectively). For mutagenicity analysis, we evaluated the frequency of micronuclei (MN) and other erythrocyte nuclear abnormalities (ENAs), while for evaluation of hepatotoxicity and neurotoxicity, livers and encephalon were analyzed for histopathological alterations. Exposure to pesticides, alone or in combination, increased the frequency of erythrocyte nuclear abnormalities, particularly blebbed nuclei, moved nuclei, and notched nuclei. Individuals exposed to fipronil exhibited congestion and inflammatory infiltrate in their liver tissue, while, in the encephalon, congestion, and necrosis were present. Our study confirms that the incubation of eggs in substrate polluted with glyphosate and fipronil causes histopathological damage and mutagenic alteration in P. expansa, highlighting the importance of using different biomarkers to evaluate the ecotoxicological effects of these pesticides, especially in oviparous animals.

Micronuclei and Nuclear Buds Induced by Cyclophosphamide in Crocodylus moreletii as Useful Biomarkers in Aquatic Environments

Simple Summary

Crocodiles are territorial reptiles that are exposed to both aquatic and terrestrial environments. Analyzing their state of health and the environment in which they live is essential to detect changes that could affect them by exposure to agents that damage their genetic material, putting their health or other species that share said habitat, including humans, at risk. There are several ways to determine exposure to harmful agents, a very simple and direct one is to analyze the nuclei of blood cells under a microscope, a test that can also be carried out directly in their habitat and that gives rapid results on the effects of agents on those at that moment they are exposed. This study demonstrates the possibility of analyzing the blood of Crocodylus moreletii to quickly analyze its exposure to toxic agents in a sample of its blood by evaluating two abnormal structures in its cells under the microscope, demonstrating that evidence of damage can be observed only by analyzing a drop of their blood.

Abstract

Micronuclei (MN) are used to assess genotoxic exposure, whereas nuclear buds (NBs) have been linked to genotoxic events. Crocodylus moreletii was studied to identify MN and NBs. Three groups were formed: Group 1 (water) and groups 2 and 3 (7 or 10 mg/kg of cyclophosphamide). A drop of blood was obtained daily from the claw tip at 0 to 120 h. Spontaneous micronucleated erythrocytes (MNEs) and erythrocytes with nuclear buds (NBEs) were counted. The frequencies of micronucleated young erythrocytes (MNYEs) and NB young erythrocytes (NBYEs) were evaluated, including the ratio of young erythrocytes (YE)/1000 total erythrocytes. No significant differences were observed in the YE proportion on sampling days; group 1 did not show differences for any parameter, whereas group 2 showed significant differences in MNEs and NBEs, and group 3 showed differences in NBEs and NBYEs. Some mitotic activity in circulation was observed in YEs. In conclusion, NBEs could be a more sensitive biomarker to genotoxic damage than MNEs. The identification of these biomarkers leads us to propose Crocodylus moreletii as a possible environment bioindicator because these parameters could be useful to analyze the in vivo health status of these reptiles and for biomonitoring genotoxic pollutants in their habitats.

Environmental impacts of COVID-19 treatment: Toxicological evaluation of azithromycin and hydroxychloroquine in adult zebrafish

One of the most impact issues in recent years refers to the COVID-19 pandemic, the consequences of which thousands of deaths recorded worldwide, are still inferior understood. Its impacts on the environment and aquatic biota constitute a fertile field of investigation. Thus, to predict the impact of the indiscriminate use of azithromycin (AZT) and hydroxychloroquine (HCQ) in this pandemic context, we aim to assess their toxicological risks when isolated or in combination, using zebrafish (Danio rerio) as a model system. In summary, we observed that 72 h of exposure to AZT and HCQ (alone or in binary combination, both at 2.5 μg/L) induced the reduction of total protein levels, accompanied by increased levels of thiobarbituric acid reactive substances, hydrogen peroxide, reactive oxygen species and nitrite, suggesting a REDOX imbalance and possible oxidative stress. Molecular docking analysis further supported this data by demonstrating a strong affinity of AZT and HCQ with their potential antioxidant targets (catalase and superoxide dismutase). In the protein-protein interaction network analysis, AZT showed a putative interaction with different cytochrome P450 molecules, while HCQ demonstrated interaction with caspase-3. The functional enrichment analysis also demonstrated diverse biological processes and molecular mechanisms related to the maintenance of REDOX homeostasis. Moreover, we also demonstrated an increase in the AChE activity followed by a reduction in the neuromasts of the head when zebrafish were exposed to the mixture AZT + HCQ. These data suggest a neurotoxic effect of the drugs. Altogether, our study demonstrated that short exposure to AZT, HCQ or their mixture induced physiological alterations in adult zebrafish. These effects can compromise the health of these animals, suggesting that the increase of AZT and HCQ due to COVID-19 pandemic can negatively impact freshwater ecosystems.

Multiple endpoints of polylactic acid biomicroplastic toxicity in adult zebrafish (Danio rerio)

Although the toxicity of conventional microplastic types (i.e., petroleum derivatives) in different organisms is already known, knowledge about the effects of alternative biopolymers on aquatic vertebrates remains incipient. Thus, the aim of the present study is to test the hypothesis that the exposure of adult Danio rerio individuals to this pollutant for 30 days is enough to cause polylactic acid biomicroplastics (BioMPs of PLA) accumulation in their bodies, which leads to behavioral/neurotoxic, biochemical, and morphological changes. Based on our results, PLA BioMPs at concentrations of 2.5 and 5 mg/L accumulated in the liver, brain, gills and carcass of the assessed animals. However, such an accumulation was not able to cause locomotor damages or to trigger anxiety-like behavior in them. On the other hand, it was enough to cause behavioral changes (in shoal) predictive of co-specific social interaction and anti-predatory defensive response deficit likely related to cholinergic changes inferred by increased acetylcholinesterase activity and REDOX imbalance. This imbalance was featured by increased production of reactive species. We observed that the treatments have affected animals' pigmentation pattern. Therefore, our study highlights the toxicological potential of the herein assessed biopolymer, and this finding puts in check the innocuousness of this material, as well as expands our knowledge about how PLA BioMPs can affect the ichthyofauna in freshwater environments.

Multiple toxicity endpoints induced by carbon nanofibers in Amazon turtle juveniles: Outspreading warns about toxicological risks to reptiles

The toxicity of carbon-based nanomaterials (CNs) has been observed in different organisms; however, little is known about the impact of water polluted with carbon nanofibers (CNFs) on reptiles. Thus, the aim of the current study was to assess the chronic effects (7.5 months) of 1 and 10 mg/L of CNF on Podocnemis expansa (Amazon turtle) juveniles (4 months old) based on different biomarkers. Increased total organic carbon (TOC) concentrations observed in the liver and brain (which suggests CNF uptake) were closely correlated to changes in REDOX systems of turtles exposed to CNFs, mainly to higher nitrite, hydrogen peroxide and lipid peroxidation levels. Increased levels of antioxidants such as total glutathione, catalase and superoxide dismutase in the exposed animals were also observed. The uptake of CNFs and the observed biochemical changes were associated with higher frequency of erythrocyte nuclear abnormalities (assessed through micronucleus assays), as well as with both damage in erythrocyte DNA (assessed through comet assays) and higher apoptosis and necrosis rates in erythrocytes of exposed turtles. Cerebral and hepatic acetylcholinesterase (AChE) increased in turtles exposed to CNFs, and this finding suggested the neurotoxic effect of these nanomaterials. Data in the current study reinforced the toxic potential of CNFs and evidenced the biochemical, mutagenic, genotoxic, cytotoxic, and neurotoxic effects of CNFs on P. expansa.

Mutagenic, genotoxic and morphotoxic potential of different pesticides in the erythrocytes of Podocnemis expansa neonates

Despite the damaging effects of pesticides glyphosate (Gly), atrazine (Atra) and fipronil (Fip) on different organisms, the mutagenic, genotoxic and morphotoxic potential of testudine erythrocytes in freshwater remains unknown. Thus, the aim of the present study is to assess the toxicological potential of these compounds in Podocnemis expansa (Amazonian turtles) neonates from eggs artificially incubated in substrate at different concentrations of herbicides Gly and Atra and insecticide Fip. Micronucleus test and other nuclear abnormalities, as well as comet assay and morphometric measurements taken of models' circulating erythrocytes were used as toxicity biomarkers. Pups exposed to Gly (groups Gly-65 ppb and Gly-6500 ppb) were the ones recording the largest amount of nuclear abnormalities; erythrocytes with multilobulated, notched and displaced nucleus were mostly frequent in groups Atra-2 ppb and Gly -65 ppb. All treatments (Gly-6500 ppb, Atra-2 ppb, Atra-200 ppb, Fip-4 ppb and Fip-400 ppb), except for group Gly-65 ppb, led to decreased erythrocyte area, increased "nuclear area: erythrocyte area" ratio, as well as to decreased erythrocyte and erythrocyte nuclei circularity, which highlights the clear effect on the size and shape of these cells. On the other hand, the comet assay did not evidence any genotoxic effect caused by the assessed pesticides. This is a pioneer study on the mutagenic and morphotoxic potential of pesticides in P. expansa eclodides exposed in ovo to Gly, Atra and Fip; therefore, it is an insight on how these compounds can affect the health of these animals.

First report on the mutagenicity and cytotoxicity of Zno nanoparticles in reptiles

Understanding how human activities affect animal biodiversity is essential to investigations about the biological effects of several pollutants and contaminants dispersed in the environment. This is the case of zinc oxide nanoparticles (ZnO NPs), which are emerging pollutants whose effect on reptiles' health is completely unknown. Thus, the objective of the present study is to evaluate the possible damages induced by these NPs in Podocnemis expansa juveniles (Amazon turtle) by using morphological changes of circulating erythrocytes as nuclear toxicity biomarker. The animals were exposed to the intramuscular administration of 440 μg/kg and 440,000 μg/kg of ZnO NPs, for 10 consecutive days. The micronuclei assay and other nuclear abnormalities were performed at the end of the experiment, as well as different morphometric measurements applied to the erythrocytes. Based on the current data, ZnO NPs induced nuclear abnormalities such as micronuclei and binucleation, which are associated with carcinogenic processes and with flaws in the mitotic machinery. The low "nuclear area: erythrocyte area" ratio and larger cytoplasmic area observed for animals exposed to NPs evidenced erythrocytic change induction likely related to negative energy balance/metabolism interferences and/or to oxygen transportation efficiency by erythrocytes. This is the first report on the mutagenic and cytotoxic effect induced by NPs on representatives of a group of reptiles. This outcome suggests that further investigations must focus on better understanding the (eco)toxicological potential of ZnO NPs.

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.