AI Article Synopsis

  • The study investigates how different forms of copper, specifically copper sulfate (CuSO) and copper oxide (CuO) engineered nanomaterials (ENMs), affect the early life stages of zebrafish, revealing that CuSO is significantly more toxic than CuO.
  • Exposure to CuSO resulted in a higher internalization of copper in embryos and associated harmful effects like depletion of essential sodium and calcium levels, while CuO showed limited internalization due to the protective chorion.
  • Overall, while both types of copper exposure led to some similar negative outcomes in the zebrafish embryos, CuSO was found to be much more harmful in terms of acute toxicity, with distinct mechanisms at play for each compound.

Article Abstract

The mechanisms of toxicity of engineered nanomaterials (ENMs) to the early life stages of freshwater fish, and the relative hazard compared to dissolved metals, is only partially understood. In the present study, zebrafish embryos were exposed to lethal concentrations of copper sulphate (CuSO) or copper oxide (CuO) ENMs (primary size ∼15 nm), and then the sub-lethal effects investigated at the LC concentrations over 96 h. The 96 h-LC (mean ± 95% CI) for CuSO was 303 ± 14 µg Cu L compared to 53 ± 9.9 mg L of the whole material for CuO ENMs; with the ENMs being orders of magnitude less toxic than the metal salt. The EC for hatching success was 76 ± 11 µg Cu L and 0.34 ± 0.78 mg L for CuSO and CuO ENMs respectively. Failure to hatch was associated with bubbles and foam-looking perivitelline fluid (CuSO), or particulate material smothering the chorion (CuO ENMs). In the sub-lethal exposures, about 42% of the total Cu as CuSO was internalised, as measured by Cu accumulation in the de-chorionated embryos, but for the ENMs exposures, nearly all (94%) of the total Cu was associated with chorion; indicating the chorion as an effective barrier to protect the embryo from the ENMs in the short term. Both forms of Cu exposure caused sodium (Na) and calcium (Ca), but not magnesium (Mg), depletion from the embryos; and CuSO caused some inhibition of the sodium pump (Na/K-ATPase) activity. Both forms of Cu exposure caused some loss of total glutathione (tGSH) in the embryos, but without induction of superoxide dismutase (SOD) activity. In conclusion, CuSO was much more toxic than CuO ENMs to early life stage zebrafish, but there are subtle differences in the exposure and toxic mechanisms for each substance.

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Source
http://dx.doi.org/10.1016/j.ecoenv.2023.114613DOI Listing

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