Oxidative stress biomarkers in the Mediterranean pond turtle (Mauremys leprosa) reveal contrasted aquatic environments in Southern France

Morphological variations and demographic responses of the Mediterranean pond turtle Mauremys leprosa to heterogeneous aquatic habitats

Human activities affect terrestrial and aquatic habitats leading to changes at both individual and population levels in wild animal species. In this study, we investigated the phenotype and demographics of the Mediterranean pond turtle Mauremys leprosa (Schweigger, 1812) in contrasted environments of Southern France: two peri-urban rivers receiving effluents from wastewater treatment plants (WWTP), and another one without sewage treatment plant. Our findings revealed the presence of pesticides and pharmaceuticals in the three rivers of investigation, the highest diversities and concentrations of pollutants being found in the river subsections impacted by WWTP effluents. Principal component analysis and hierarchical clustering identified three levels of habitat quality, with different pollutant concentrations, thermal conditions, nutrient, and organic matter levels. The highest turtle densities, growth rates, and body sizes were estimated in the most disturbed habitats, suggesting potential adult benefits derived from harsh environmental conditions induced by pollution and eutrophication. Conversely, juveniles were the most abundant in the least polluted habitats, suggesting adverse effects of pollution on juvenile survival or adult reproduction. This study suggests that turtles living in polluted habitats may benefit from enhanced growth and body size, at the expense of reproductive success.

Enteric parasites in free-living Mediterranean pond turtle (Mauremys leprosa leprosa) in contrasted areas (natural vs polluted) from central-western of Morocco

The objective of this study is to assess the occurrence of intestinal parasites in Mediterranean pond turtle Mauremys leprosa leprosa collected from three contrasting environments in Morocco. Stool samples from 92 turtles were examined for parasite detection and enumeration. The identified intestinal parasites belong to helminths (oxyurids and ascarid) and protozoa (Entamoebidae). A total of 25 turtles (27.17%) were found to be infected by helminths and/or protozoan parasites. No adult form of these parasites was detected. Eggs of oxyurid and ascarid were detected in individuals of populations studied from Oued Ksob (23.07% and 30.76% of n = 13 turtles) and Oued Zat (34.14% and 24.39% of n = 41 turtles), respectively. For protozoa, Entamoeba cysts were present in turtles in Oued Ksob (15.38% of n = 13 turtles), Oued Zat (12.19% of n = 41 turtles), and Oued Tensift (5.26% of n = 38 turtles) localities. Oxyurid eggs showed the highest intensity at Oued Zat reaching 29.30 ± 59.59 eggs per gram (EPG), versus 12 ± 0.38 EPG for ascaris eggs in Oued Ksob. Entamoeba cysts were detected in lower levels with a maximum of 1.66 ± 1.50 cysts per gram (CPG), in Oued Zat. The prevalence of turtles eliminating eggs was statistically significant between localities for different parasite groups. This study reports for the first time a parasitological characterization of gastrointestinal parasites in wild populations of M. leprosa leprosa from contrasting environments, suggesting a relationship between turtles' infestation and the quality of their habitat.

Effects of glyphosate, 2,4-D, chlorantraniliprole, and imidacloprid formulations, separately and in mixtures in Caiman latirostris hatchlings

The present study demonstrated the potential of glyphosate (GLY), 2,4-dichlorophenoxyacetic acid (2,4-D), imidacloprid (IMI) and chlorantraniliprole (CAP) separately and in mixtures to induce oxidative stress and DNA damage in Caiman latirostris hatchlings. Under controlled condition, an embryonic exposure to these pesticides was done at concentrations recommended for soybean crops. Treatments were: negative control, GLY, 2,4-D, IMI, CAP, mixture 1 (M1): GLY + 2,4-D, M2: IM I + CAP and M3: GLY + 2,4-D + IMI + CAP. At hatching, blood samples were taken for the evaluation of genotoxicity, oxidative damage to lipids and DNA, the enzymatic activity of Catalase (CAT) and Superoxide dismutase (SOD), and the expression level of their corresponding genes (catalase: cat and superoxide dismutase: sod). It has been shown that IMI, M2 and M3 induced a significant inhibition of CAT activity while no effect was observed on SOD. In turn, lipid peroxidation was significantly higher in individuals exposed to IMI, and to all the mixtures. Besides, genotoxicity and oxidative DNA damage were observed in all exposed groups. The results of mRNA expression showed no difference at transcription levels. In the same way, no alterations in growth parameters were recorded at hatching. Regarding to the mixtures, we observed a potentiating action of IMI on M3 in lipid peroxidation as well as independent action on oxidative DNA damage and genotoxicity parameters. Our results highlight the importance of investigating the effect of pesticides and their mixtures considering the potential consequences to caimans living in natural environments.

Population structure and dynamics of the Mediterranean Pond turtle Mauremys leprosa (Schweigger, 1812) in contrasted polluted aquatic environments

Pollution contributes to the degraded state of continental aquatic ecosystems and biodiversity. Some species appear to be tolerant to aquatic pollution, yet little is known about the effects of such pollution on population structure and dynamics. Here, we investigated how wastewater treatment plant (WWTP) effluents of the Cabestany City, in southern France, contribute to the pollution levels of the Fosseille River, and we tested how they could affect population structure and medium-term dynamics of the native freshwater turtle, the Mediterranean Pond Turtle Mauremys leprosa (Schweigger, 1812). Amongst the 68 pesticides surveyed from water samples collected along the river in 2018 and 2021, a total of 16 pesticides were detected, among which eight were found in the upstream section of the river, 15 in the river section located downstream of the WWTP, and 14 in the outfall of the WWTP, exhibiting the contribution of effluents to the river pollution. From 2013 to 2018 and in 2021, capture-mark-recapture protocols were carried out on the freshwater turtle population living in the river. Using robust design and multi-state models, we showed a stable population throughout the study period, with high year-dependent seniority, and a bidirectional transition occurring primarily from the upstream to the downstream river sections of the WWTP. The freshwater turtle population consisted mostly of adults, with a male biased sex ratio detected downstream of the WWTP neither related to sex-dependent survival, recruitment, nor transition, suggesting a male bias in the hatchlings or primary sex ratio. Also, the largest immatures and females were captured downstream of the WWTP, with females having the highest body condition, whereas no such differences were observed in males. This study highlights that population functioning of M. leprosa is driven primarily by effluents induced resources, at least over the medium-term.

Minor metabolomic disturbances induced by glyphosate-isopropylammonium exposure at environmentally relevant concentrations in an aquatic turtle, Pelodiscus sinensis

The ecotoxicological and environmental impacts of glyphosate-based herbicides have received considerable attention due to their extensive use globally. However, the potential for adverse effects in cultured non-fish vertebrate species are commonly ignored. In this study, effects on growth, indicators of functional performance, gut microbial diversity, liver antioxidant responses and metabolite profiles were evaluated in soft-shelled turtle hatchlings (Pelodiscus sinensis) exposed to different concentrations of glyphosate-isopropylammonium (0, 0.02, 0.2, 2 and 20 mg/L). No significant changes in growth or functional performance (food intake, swimming speed), gut microbiota, and liver antioxidant responses (SOD and CAT activities, MDA content) were observed in exposed turtles. However, hepatic metabolite profiles revealed distinct perturbations that primarily involved amino acid metabolism in turtles exposed to environmentally relevant concentrations. Overall, our results suggested that metabolite profiles may be more sensitive than phenotypic or general physiological endpoints and gut microbiota profiling, and indicate a potential mechanism of hepatotoxicity caused by glyphosate-isopropylammonium based on untargeted metabolomics analysis. Furthermore, the toxicity of glyphosate at environmentally relevant concentrations might be relatively minor in aquatic turtle species.

How the exposure to environmentally relevant pesticide formulations affects the expression of stress response genes and its relation to oxidative damage and genotoxicity in Caiman latirostris

This study aimed to analyze the molecular stress responses thought the expression levels of catalase (cat), superoxide dismutase (sod) and heat shock protein 70 (hsp70) genes, and how these relate with cellular stress response considering oxidative damage to lipids, DNA and genotoxicity in blood of Caiman latirostris hatchlings exposed to pesticide formulations under ex situ conditions. Treatments were: negative control (NC-tap water), glyphosate 2% (GLY), cypermethrin 0.12% (CYP), chlorpyrifos 0.8% (CPF), and their ternary mixture (Mx3). The concentrations and schedule of application were those recommended in soybean crops. Soil and water showed pesticides residues in all exposed groups. Results showed a statistically significant increase in the micronucleus frequency and DNA damage, with an important oxidation in all exposed groups. The expression level of cat gene was significantly higher in CYP while the expression of hsp70 was significantly lower in GLY, CYP and Mx3, compared to NC. Pesticides tested showed alterations in expression levels, growth parameters, DNA damage and base oxidation under realistic exposure conditions, and can threaten, in the long term, the health status of wild populations.

Alterations in the Expression of Antioxidant Enzyme Genes in Response to Pesticide Exposure During Embryonic Development in the Native Reptile Species Caiman latirostris

The aim of this study was to quantify the expression levels of Catalase (cat) and copper, zinc Superoxide dismutase (Cu, Zn-sod) genes involved in the antioxidant response in Caiman latirostris (broad-snouted caiman) blood, after embryonic exposure to the formulations cypermethrin (CYP), chlorpyrifos (CPF), glyphosate (GLY), and their binary and ternary mixtures. Experimental groups were: negative control (NC-distilled water), vehicle control (VC-ethanol), GLY-2%, CYP- 0.12%, CPF- 0.8%, a ternary mixture of them (TM), and three binary mixtures. The applications were made on the nest material in contact with the eggs at the beginning of the incubation period. After hatching, RNA was isolated from blood and expression levels analyzed through qPCR. The results showed downregulation in the expression of sod and cat genes in the three binary mixtures studied, compared to the controls. In addition, we found a possible antagonistic effect between different pesticides in the TM on the expression of both genes.

In situ exposure of amphibian larvae (Rhinella fernandezae) to assess water quality by means of oxidative stress biomarkers in water bodies with different anthropic influences

In situ bioassays provide valuable information about the environment and offer more realistic results than usual laboratory experiments. The aim of this study was to evaluate the quality of water bodies from the lower Paraná River basin, the second most important in South America, through analysis of physiochemical parameters, metals and pesticides and in situ exposure of Rhinella fernandezae larvae to assess oxidative stress biomarkers. The sites were: S1(Morejón stream, reference); S2, S3(De la Cruz stream upstream and downstream, respectively) and S4(Arrecifes River). In all sites, dissolved oxygen was low, atrazine was detected and Cu was higher than the limit for aquatic life protection. According to the water quality index, S2, S3 and S4 presented bad water quality, while S1 good water quality. Larvae were exposed in situ for 96h in order to analyze: lipid peroxidation(TBARS) as oxidative damage, antioxidant enzymatic (catalase-CAT-, superoxide dismutase-SOD- and glutathione s-transferase-GST-) and non-enzymatic defenses (reduced glutathione-GSH-). Larvae exposed in the most impacted sites (S2, S3 and S4) presented oxidative stress since the levels of TBARS were around 2 times higher than in S1. Also, the other oxidative stress biomarkers were altered in larvae exposed at S2, S3 and S4. These results highlight the importance of analyzing oxidative stress biomarkers during in situ exposures since they are useful tools for documenting the extent of exposure at sublethal levels. The complex pollution of the water bodies affected the exposed larvae, which may jeopardize the native populations.

Lipid peroxidation of kidney of the turtle Mauremys reevesii caused by cadmium

This research was designed to investigate lipid peroxidation of the kidney of turtle (Mauremys reevesii) caused by cadmium. Turtles were injected intraperitoneally with cadmium at the concentration of 0 (control), 7.5, 15, and 30 mg/kg, and 5 turtles were taken from each group after exposure for 1 week (1 w), 2 weeks (2 w), and 3 weeks (3 w). Superoxide dismutase (SOD) and catalase (CAT) activities as well as glutathione (GSH) and malonyldialdehyde (MDA) contents in the homogenate of kidney tissue were analyzed. The results demonstrated that a short time of low dose of cadmium could stimulate the increase of SOD activity in the kidney of turtles, but a long time of high dose of cadmium could induce the decrease of SOD activity in the kidney of turtles. Cadmium could decrease CAT activity and GSH content in turtle kidney, but increased MDA content in turtle kidney. There were some other effects on the turtles, such as depression and diarrhea. The experimental results indicate that cadmium causes temporary oxidative stress on the kidney of turtles.

Oxidative stress in liver of turtle Mauremys reevesii caused by cadmium

The research was designed to examine oxidative stress of the liver of turtle Mauremys reevesii caused by cadmium (Cd). Turtles were injected intraperitoneally with cadmium at the concentration of 7.5, 15, and 30 mg/kg, and 5 turtles were taken from each group after exposure for 1 week (1 w), 2 weeks (2 w), and 3 weeks (3 w). The activities of SOD and CAT as well as the contents of GSH and MDA in liver tissues were detected by using a kit. The results showed that the difference between the control group and the Cd-treated group was statistically significant with the increase of Cd concentration and the prolongation of exposure time, which suggested that Cd caused oxidative stress on the liver of turtles.

How Glyphosate Impairs Liver Condition in the Field Lizard Podarcis siculus (Rafinesque-Schmaltz, 1810): Histological and Molecular Evidence

The potential toxicity of glyphosate, a widely used broad-spectrum herbicide, is currently a great matter of debate. As vertebrate insectivores, lizards protect plants from herbivorous insects increasing plant biomass via the trophic cascade and represent an important link between invertebrates and higher predators. A negative effect of glyphosate on lizards' survival could have major impacts at the ecological levels. In this study, we investigated the effects of the exposure to low doses of glyphosate on the liver of the wall lizard Podarcis siculus, a suitable bioindicator of soil pollution. Two different doses of pure glyphosate (0.05 and 0.5 μg/kg body weight) were orally administered every other day for 3 weeks to sexually mature males and females. The results demonstrated that both doses, despite being very low, are toxic for the liver that showed clear signs of suffering, regardless of sex. The histological analysis provided a scenario of severe hepatic condition, which degenerated until the appearance of fibrotic formations. The morphological observations were consistent with a loss of liver physiological functions. Immunocytochemical investigations allowed us to detect an involvement of antioxidant/cytoprotective proteins, such as superoxide dismutase 1 (Cu/Zn SOD, known as SOD1), glutathione peroxidase 1 (GPx1), metallothionein (MT), and tumor suppressor protein 53, (p53) suggesting that the liver was trying to react against stress signals and damage induced by glyphosate. Finally, in situ hybridization and Real-Time PCR analysis showed the upregulation of estrogen receptor α and vitellogenin gene expression, thus demonstrating the xenoestrogenic action of glyphosate. The imbalance of the hormonal homeostasis could threaten the lizards' reproductive fitness and survival, altering the trophic cascade.

Morphological and physiological assessments reveal that freshwater turtle (Mauremys leprosa) can flourish under extremely degraded-polluted conditions

Freshwater turtles are long-lived sedentary organisms used as biological sentinels to assess anthropogenic perturbations in freshwater-ecosystems; notably because pollutants tend to accumulate in their tissues. Pollution has detrimental effects in sea turtles, but studies in freshwater turtles have provided contrasted results: several species have been impacted by habitat perturbation and pollution while others not. It is important to explore this issue since freshwater turtles are threatened worldwide. We compared two populations of the stripe necked terrapin (Mauremys leprosa) in a relatively pristine area (piedmont of the Atlas mountain) versus an extremely degraded-polluted area (sewers of a large city) in Morocco. All morphological and physiological proxies showed that turtles were able to cope remarkably well with highly degraded-polluted habitat. Population density, body size, and body condition were higher in the sewers, likely due to permanent water and food availability associated with human wastes. Stress markers (e.g. glucocorticoids) provided complex results likely reflecting the capacity of turtles to respond to various stressors. Reproductive parameters (testosterone level, indices of vitellogenesis) were lower in the relatively pristine area. The deceptive overall image provided by these analyses may hide the disastrous human impact on rivers. Indeed, Mauremys leprosa is the only aquatic vertebrate able to survive in the sewers, and thus, might nonetheless be a pertinent indicator of water quality, providing that the complexity of eco-physiological responses is considered.

Oxidative damage and antioxidant defense in Caiman latirostris (Broad-snouted caiman) exposed in ovo to pesticide formulations

The surface used for agricultural production in Argentina significantly increased in recent years, mainly due to the expansion of soybean crops. As a result, the use of agrochemicals increased too. Many natural populations of Caiman latirostris (broad-snouted caiman) are affected by habitat fragmentation and the constant exposure to pesticides. This exposure could produce Reactive Oxygen Species. The negative imbalance between ROS generation and the capacity of the biological systems to eliminate the reactive intermediaries or avoid the damage is called Oxidative Stress. The aim of this study was to evaluate oxidative damage and antioxidant defense in C. latirostris hatchlings after in ovo exposure to widely used pesticide formulations. Embryos were exposed by topical exposure on the eggshell, from the beginning of incubation period, to sub-lethal concentrations of two glyphosate formulations: PanzerGold® (PANZ) and Roundup® Full II (RU): 500, 750, 1000 μg/egg; to the endosulfan (END) formulation Galgofan® and the cypermethrin (CYP) formulation Atanor®: 1, 10, 100, and 1000 μg/ egg. Blood samples were taken to all animals immediately after hatching for the application and comparison of the following oxidative stress biomarkers between the exposed groups and their respective controls: lipoperoxidation through thiobarbituric acid reactive substances (TBARS), DNA base oxidation through the modified comet assay, and the activities of Catalase (CAT) and Superoxide dismutase (SOD) in erythrocytes. Our results showed lipoperoxidation in caiman exposed to END (10, 100, 1000 µg/egg), CYP (1, 10, 1000 µg/egg), RU (500, 1000 µg/egg) and PANZ (500, 1000 µg/egg), DNA base oxidation in those exposed to END (10, 100, 1000 µg/egg), CYP (1, 10 µg/egg) and PANZ (500, 750 µg/egg) as well as alteration in the activity of SOD in END 1 µg/egg and CYP (10, 1000 µg/egg). This study demonstrated the incidence of oxidative stress in animals exposed to pesticide formulations widely used in agricultural activity associated mainly with soybean crops, and add further information to that previously reported about pesticide effects in this native reptile species.