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The aim of this study was to investigate the crosstalk between oxidative stress and autophagy through the ROS/HO-1/NQO1 pathway caused by copper (Cu). Duck renal tubular epithelial cells were treated in Cu sulfate (CuSO 4) (0, 100 and 200 μM) for 12 h, and in the combination of CuSO 4 (200 μM) and reactive oxygen species (ROS) scavenger (butyl hydroxyanisole, BHA, 100 μM), or HO-1 inhibitor (zinc protoporphyrin, ZnPP, 10 μM) for 12 h. Results revealed that Cu could significantly elevate the levels of intracellular ROS, superoxide dismutase, hydrogen peroxide, malondialdehyde, glutathione, simultaneously reduce catalase and glutathione peroxidase levels, and upregulate HO-1, SOD-1, CAT, NQO1, GCLM mRNA levels and HO-1, SOD-1 protein levels. Additionally, Cu could observably increase the number of autophagosomes, acidic vesicle organelles (AVOs) and LC3 puncta; upregulate mRNA levels of mTOR, Beclin-1, ATG7, ATG5, ATG3, LC3II and protein levels of Beclin-1, LC3II/LC3I, downregulate LC3I mRNA level. Both treatments with BHA and ZnPP could significantly alleviate the changes of antioxidant indexes levels and ROS accumulation, reduce the increase of the number of autophagosomes, AVOs and LC3 puncta, and mitigate the above changed oxidative stress and autophagy related mRNA and protein levels induced by Cu. In summary, our findings indicated that excessive Cu could induce oxidative stress and autophagy by activating the ROS/HO-1/NQO1 pathway, and inhibition of HO-1 might attenuate Cu-induced oxidative stress and autophagy in duck renal tubular epithelial cells. Unlabelled Image • Copper (Cu) induced oxidative stress in duck renal tubular epithelial cells. • Autophagy occurred in duck renal tubular epithelial cells induced by Cu. • High levels of heme oxygenase-1 (HO-1) aggravated Cu-induced oxidative stress. • Inhibition of HO-1 might attenuate Cu-induced autophagy. • Cu caused oxidative stress and autophagy through ROS/HO-1/NQO1 pathway. [ABSTRACT FROM AUTHOR]

Magnetic Fe 3 O 4 -encapsulated C 3 N 3 S 3 polymer/reduced graphene oxide composite (rGO-poly(C 3 N 3 S 3 )/Fe 3 O 4 ) was synthesized to remove Pb(II) and Hg(II) from aqueous solutions. This material was characterized by X-ray Photoelectron Spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, N 2 adsorption, etc. The results suggest that final composite exhibits two-dimensional (2D) nanosheet structure, in which Fe 3 O 4 nanoparticles or clusters are encapsulated between the layers of rGO-poly(C 3 N 3 S 3 ) matrix, preventing composite aggregation and nanoparticle detachment. The results of adsorption tests suggested high metal removal and short residence time to reach equilibrium. The adsorption kinetics data were well fitted by pseudo-second-order equation. The effect of metal concentration on adsorption was illustrated by Langmuir isotherm equation. Maximum metal-uptake capacities for Pb(II) and Hg(II) ions were 270.3 and 400.0 mg/g, respectively. High-resolution XPS spectra clearly illustrate the adsorption mechanism, in that Hg(II) preferentially binds to sulphur functional groups and Pb(II) tends to be adsorbed by nitrogen groups in poly(C 3 N 3 S 3 ) matrix. Recycling performance of this composite was investigated in 15 consecutive adsorption-desorption cycles, after which the adsorption capacities for Pb(II), and Hg(II) ions remain stable thanks to Fe 3 O 4 encapsulation into the rGO-poly(C 3 N 3 S 3 ) matrix., (Copyright © 2018 Elsevier B.V. All rights reserved.)