“…There were no statistically significant differences in the amount of copper accumulated in embryos exposed to 50 ppb of CuSO 4 , 2000 ppb of synthesized nano-CuO, and 1900 ppb and 19 000 ppb of commercial nano-CuO (5.3 ± 1.1, 7.9 ± 0.8, 6.3 ± 1.5 and 11.9 ± 3.4 ng of copper/mg wet weight, respectively, Figure 6A). Although protein oxidation has been used as an oxidative stress indicator (Shacter, 2000), and has been reported in mussels (Hu et al, 2014) and in sea urchin embryos (Wu et al, 2015) exposed to nano-CuO, we did not observe such protein oxidation in any of the treatments (Supplementary Figure S2). In contrast, there was a significant decrease in TAOC in embryos exposed to 2000 ppb of synthesized nano-CuO (74 ± 1.9% of control), and was even lower in embryos exposed to 19 000 ppb of commercial nano-CuO (57 ± 2.1% of control, Figure 6B).…”