Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2025Scopus SJRQ3/r/munzur/1343
  Antioxidant Enzyme Responses to Lead Exposure in Daphnia magna

  Sahilli, Yeliz Cakir

  Abstract: Lead (Pb), a pervasive environmental contaminant, poses significant toxicological risks to freshwater ecosystems. Daphnia magna, a widely used model organism in aquatic toxicology, provides valuable insights into the sublethal effects of heavy metal exposure. This study investigated the effects of Pb exposure on antioxidant defense mechanisms in D. magna. Test organisms were exposed to aqueous Pb solutions at varying concentrations (0, 10, 20, 30 μg/L) for 96 h. The enzyme activities of glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) were measured using enzyme-linked immunosorbent assay (ELISA). SOD activity did not differ significantly between the exposed and control groups. However, CAT activity showed a significant decrease in all Pb-exposed groups compared to controls. GPx activity exhibited a non-significant decrease. In conclusion, Pb exposure may induce oxidative stress by generating reactive oxygen species (ROS) and inhibiting the function of sulfhydryl-containing antioxidant enzymes. Changes in antioxidant enzyme activity may serve as early biomarkers in ecotoxicological assessments of Pb pollution in aquatic environments. It is suggested that future studies incorporate molecular-level endpoints and chronic exposure scenarios to better elucidate the long-term impacts of Pb on aquatic invertebrates.

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• MakaleYalnız künye2025Scopus SJRQ3/r/munzur/1211
  Oxidative and Antioxidant Responses in Daphnia magna Following Exposure to Sub-Lethal Glyphosate Concentrations

  Sahilli, Yeliz Çakir; Korkmaz, Volkan

  Abstract: Glyphosate (GLY) is one of the most widely used herbicides in modern intensive agriculture to enhance crop production. However, the chemical additives in commercial formulations and the active ingredient itself can adversely affect biological and chemical processes in aquatic organisms. Therefore, the aim of this study was to evaluate the effects of sub-lethal concentrations of GLY (0, 0.23, 0.58, and 1.17 μg/L) on oxidative stress biomarkers—namely lipid peroxidation (measured as malondialdehyde, MDA), and antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and reduced glutathione, GSH)—in Daphnia magna after 24 and 96 h of exposure. The results showed that SOD activity increased in all treatment groups compared to the control at both time points while CAT activity decreased in all groups. GSH and TBARS (thiobarbituric acid reactive substances) levels were significantly elevated after 24 and 96 h in all exposed groups. Overall, D. magna was sensitive to sub-lethal concentrations of GLY, and changes in SOD and CAT activities, as well as GSH and TBARS levels, these biomarkers can serve as useful indicators for detecting glyphosate-induced oxidative stress and water pollution.

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