Comparative effects of the two copper compounds: Copper chloride and copper sulfate on bioaccumulation, fecundity, and stress responses in the brine shrimp Artemia franciscana.

To evaluate the toxicological impacts of the two copper formscopper chloride (CuCl₂) and copper sulfate (CuSO4), on the brine shrimp Artemia franciscana, we examined the bioaccumulation, life cycle parameters (survival and hatching rates), reactive oxygen species (ROS), antioxidant enzymatic activities (e.g., glutathione S-transferase [GST], glutathione peroxidase [GPx], and superoxide dismutase [SOD]) with transcriptional expression of heat shock protein (hsp) genes in response to CuCl₂ and CuSO4. Higher accumulation rates of CuCl₂ and CuSO4 were observed in concentration- and time-dependent manners. Based on this investigation, significant reductions in survival and hatching success were observed in response to CuCl₂ and CuSO4. The two forms of copper, CuCl₂ and CuSO4, have also induced marked changes in reactive oxygen species (ROS) levels and antioxidant enzyme activities, indicating ROS-mediated oxidative stress and activation of defense mechanisms, resulting in adverse effects on survival and hatching successes of A. franciscana. Additionally, transcriptional analysis has revealed modulation of the four hsp genes (hsp26, hsp40, hsp70, and hsp90) in response to CuCl₂ and CuSO4. In particular, hsp40 and hsp90 were significantly upregulated in response to CuCl₂ and CuSO4, suggesting that hsp genes likely play important role in cellular defense mechanisms and hsp40 and hsp90 could be useful as potential biomarkers for CuCl₂ and CuSO4 toxicity. Overall, the results of this study provide valuable information for understanding the underlying effects in response to CuCl₂ and CuSO4 in aquatic zooplankton.