Oxidative and Antioxidant Responses in Daphnia magna Following Exposure to Sub-Lethal Glyphosate Concentrations

Polystyrene is widely used in disposable products and is now a ubiquitous plastic pollutant in aquatic environments, where it degrades into smaller particles that leach potentially toxic chemicals. However, knowledge regarding the impacts of plastic leachates remains limited. This study investigates the lethal and nonlethal effects of polystyrene leachate on two ecologically significant aquatic organisms, Daphnia magna (water flea) and Artemia salina (brine shrimp). Polystyrene leachates were prepared in seawater, freshwater, and sterile, pure water by incubating the material in each of the media under natural conditions for six months. D. magna and A. salina were exposed to varying concentrations of the leachates under controlled laboratory conditions, monitoring their survival, as well as measuring reactive oxygen species and antioxidant responses as superoxide dismutase and catalase activity. The data show that A. salina was more significantly affected with higher mortality observed at lower leachate concentrations, potentially linked to seawater enhancing the leaching of toxic additives. Moreover, at non-lethal concentrations, the antioxidative responses maintained homeostasis in both organisms. Considering the current reported microplastic concentrations in the aquatics and the adequate antioxidative response, leachate from plastic potentially does not pose a severe threat to these organisms. Nevertheless, hydrological characteristics of waterbodies may cause microplastic hotspots, which could significantly concentrate plastics and thus their leachates, necessitating action to reduce the current microplastic pollution level and avoid future surges. This study highlights the ecological significance of polystyrene pollution, emphasizing the need for more comprehensive regulatory measures and the development of sustainable alternatives to polystyrene-based products. The distinct responses of D. magna and A. salina imply that the impact of plastic pollution varies among species, necessitating further research to elucidate broader ecological consequences. Understanding how polystyrene leachate affects keystone species provides crucial insights into the overall implications for aquatic ecosystems.

Nickel and binary metal mixture responses in Daphnia magna: Molecular fingerprints and (sub)organismal effects

Phototoxicity and oxidative stress responses in Daphnia magna under exposure to sulfathiazole and environmental level ultraviolet B irradiation

Suspended particles (SP) exist widely in various water systems and are able to adsorb other pollutants in water, producing ecotoxic effects on aquatic nontarget species. Until now, however, few studies have focused on the effects of SP on antibiotics. Therefore, the present study investigated the effects of the mixtures of SP and phenicol antibiotics (chloramphenicol [CAP], thiamphenicol [TAP]) on acute toxicity and oxidative stress responses in Daphnia magna. The results indicated that the acute toxicity of phenicol antibiotics in D. magna was increased when combined with SP. Besides, the immobilization of daphnids caused by phenicol drugs in the presence of 10 mg/L of SP was more intense than that with 200 mg/L of SP. Furthermore, the impact of SP with diverse concentrations on the activity of catalase and the level of reduced glutathione in D. magna was different. Notably, almost all CAP + TAP + SP treatments markedly increased malondialdehyde content in D. magna, causing potential cellular oxidative damage in D. magna. In summary, the present study provides insights into the toxic effects of phenicol antibiotic and SP mixtures on aquatic organisms. Environ Toxicol Chem 2021;40:2463-2473. © 2021 SETAC.

Natural populations are confronted with multiple selection pressures resulting in a mosaic of environmental stressors at the landscape level. Identifying the genetic underpinning of adaptation to these complex selection environments and assigning causes of natural selection within multidimensional selection regimes in the wild is challenging. The water flea Daphnia is a renowned ecological model system with its well-documented ecology, the possibility to analyse subfossil dormant egg banks and the short generation time allowing an experimental evolution approach. Capitalizing on the strengths of this model system, we here link candidate genome regions to three selection pressures, known to induce micro-evolutionary responses in Daphnia magna: fish predation, parasitism and land use. Using a genome scan approach in space, time and experimental evolution trials, we provide solid evidence of selection at the genome level under well-characterized environmental gradients in the wild and identify candidate genes linked to the three environmental stressors. Our study reveals differential selection at the genome level in Daphnia populations and provides evidence for repeatable patterns of local adaptation in a geographic mosaic of environmental stressors fuelled by standing genetic variation. Our results imply high evolutionary potential of local populations, which is relevant to understand the dynamics of trait changes in natural populations and their impact on community and ecosystem responses through eco-evolutionary feedbacks.

Impact of black phosphorus nanosheet exposure on growth, reproduction, antioxidant mechanisms, and transcriptomic responses in Daphnia magna.

Background: Traffic-related air pollution is associated with cardiovascular morbidity and mortality. Although the biological mechanisms are not well understood, oxidative stress may be a primary pathway. Subpopulations, such as individuals with metabolic syndrome (MeS), may be at increased risk of adverse effects associated with air pollution. Our aim was to assess the relationship between exposure to diesel exhaust (DE) and indicators of systemic antioxidant and oxidative responses in adults with MeS. We hypothesized that DE exposure would result in greater oxidative stress and antioxidant responses compared with filtered air (FA).Methods: Ten adult subjects with MeS were exposed on separate days for two hours to FA or DE (at 200μg/m3), in a double blind, crossover experiment. Urinary 8-isoPGF2α (F2-isoprostanes), and 8-hydroxy-2’-deoxyguanosine (8-OHdG) were assessed as markers of oxidative stress at 3 hrs and 22 hrs, respectively, after exposure initiation. To assess the short-term antioxidant response we analyzed plasma ascorbic acid (AA) 90 minutes after exposure initiation. All outcomes were compared to pre-exposure levels, and mean changes were compared between FA and DE exposures.Results: Mean changes in urinary F2-isoprostanes (ng/mg creatinine), (−0.05 [95% CI = −0.29, 0.15]), and 8-OHdG (μg/g creatinine) (−0.09 [−0.13, 0.31]), were not statistically significant. Mean changes in plasma AA (mg/dl) were also not significant (−0.02 [−0.78, 0.04]).Conclusions: In this carefully controlled experiment, we did not detect significant changes in oxidative stress or systemic antioxidant responses in subjects with MeS exposed to 200μg/m3 DE.

Metabolomics identified distinct molecular-level responses in Daphnia magna after exposure to phenanthrene and its oxygen and nitrogen containing analogs.

With global warming, it is crucial to recognise that temperature changes can influence the ecotoxicity of pollutants in natural ecosystems. 4-Chloroaniline (4-CA) is an emerging contaminant due to its environmental persistence, bioaccumulation potential, and toxicity to aquatic organisms. This study intends to assess the effects of environmentally relevant concentrations of 4-CA (0.09-9.65µg/L) on Daphnia magna under two temperatures: 20°C (standard) and 26°C (global warming). A 21-day reproduction assay evaluated the life-history traits and biomarkers related to oxidative stress, metabolism, neurotoxicity, genotoxicity, and cellular energy allocation. Results revealed an interaction between temperature and 4-CA exposure. At 26°C, D. magna exhibited anticipation of reproduction and increased brood frequency but with fewer offspring per brood. Thermal stress also intensified metabolism and antioxidant defences, with elevated superoxide dismutase and glutathione peroxidase activities, suggesting a compensatory mechanism to mitigate oxidative damage. Genotoxicity was more pronounced at 26°C, highlighting an increased risk of DNA damage. The combined stress of 4-CA and temperature negatively impacted energy allocation, reproductive success, and overall fitness. The results underscore the importance of incorporating climate change scenarios into ecotoxicological assessments of emergent contaminants, reinforcing the need to include 4-CA in the Water Framework Directive Watch List.

Reactive oxygen species (ROS) and redox buffers as an interface between stress sensing, signalling and physiological responses in Daphnia magna

Systemic and metabolic responses in Daphnia magna to anoxia

Ecological risks of combination of multiple pollutants at environmentally relevant concentrations: Insights from the changes in life history traits, gut microbiota, and transcriptomic responses in Daphnia magna

Aggregation and dissolution of CuO and ZnO nanoparticles (NPs) increased with increasing exposure time (24, 48, and 72h). Acute toxicity of CuO NPs to Daphnia magna also increased significantly with increasing exposure time (p < 0.05), whereas exposure time did not significantly affect acute toxicity of ZnO NPs. The dissolved Cu concentration of CuO NPs was much lower than the median effective concentration (EC50) value (44μgL-1 at 72h), implying that the increase in acute toxicity was caused by particles rather than by dissolved ions. However, the dissolved Zn concentration of ZnO NPs was higher than the EC50 value (600μgL-1 at 72h), suggesting this acute toxicity may be caused by dissolved ions. Moreover, CuO NPs induced greater lipid peroxidation than Cu ions did at an exposure time of 72h, whereas converse results were observed for ZnO NPs.

Molecular Mechanisms that Regulate Scopolamine Effects on Inducible Fish Antipredation Responses in Daphnia Magna

Ecotoxicological consequences of polystyrene naturally leached in pure, fresh, and saltwater: lethal and nonlethal toxicological responses in Daphnia magna and Artemia salina