Abstract:

Objective To study the effect of copper on microstructures and ultrastructures of gill of zebrafish, antioxidant defense system of superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and related immune factors ［tumor necrosis factor alpha (TNF-alpha), interleukin（IL）-6, IL-1 beta) ］in the acute toxicity test.Methods Three copper exposures (0.05 mg/L, 0.1 mg/L, 0.2 mg/L) and a control group were set in this study. Results The copper exposure groups showed varying degrees of damage, such as the epithelial cell swelling, shedding, surface mucus, basal cell hyperplasia and gill lamellae fusion under the light microscope. The mitochondria and rough endoplasmic reticulum cell were swelled, and mitochondrial cristae collapse or the disappearance of oncosis morphology were observed under transmission electron microscope(TEM). SOD activity and MDA content extended upward as increase of the copper ion concentration and exposure time. In addition, copper ion exposure on zebrafish SOD, MDA as compared with the control, showed an induction effect. Compared to the control group, TNF-alpha, IL-6, and IL-1 beta levels increased by different extents after treatment with different concentrations of copper and time. Conclusion The heavy metal copper has obvious damage and immune toxicity to the gill structure and antioxidant system of zebrafish.

Key words: Copper, Tissue structure, Antioxidant system, Immune factor, Transmission electron microscopy, Zebrafish