The effects of zinc chloride during early embryonic development in zebrafish (Brachydanio rerio)

This study investigated the developmental toxicity of zinc chloride (ZnCl2) in zebrafish embryos (Brachydanio rerio, Cyprinidae, Cypriniformes). Zebrafish embryos were exposed to 5 different concentrations of ZnCl2, from the blastula stage, for 15 days under static renewal test conditions. As a result, the corresponding median lethal concentration (LC50) value determined for ZnCl2 exposure was 1.36 mg/L (0.65 mg/L as a lone Zn2+ ion). At 1.0 mg/L ZnCl2, the exposed group’s hatching began at 7 days instead of at 4 days, and most of the embryos died in the chorion without hatching at 11 and 12 days. Developmental deformities such as abnormal embryogenesis, low hatchability, delayed hatching, and reduction of newly hatched larvae, and a poor survival ratio (mortality ratio of 1.5 and 10 mg/L concentrations compared to control, P < 0.001), were observed during the embryo larval stage due to zinc exposure. Based on these results, we observed that critical and teratogenic effects of ZnCl2 on embryonic development of zebrafish occurred at concentrations greater than 0.5 mg/L. Moreover, our results confirm that the zebrafish embryo teratogenesis assay can be a useful pretest for integrated biological hazard assessment of chemical agents used in industrial production and drug development technologies.This study investigated the developmental toxicity of zinc chloride (ZnCl2) in zebrafish embryos (Brachydanio rerio, Cyprinidae, Cypriniformes). Zebrafish embryos were exposed to 5 different concentrations of ZnCl2, from the blastula stage, for 15 days under static renewal test conditions. As a result, the corresponding median lethal concentration (LC50) value determined for ZnCl2 exposure was 1.36 mg/L (0.65 mg/L as a lone Zn2+ ion). At 1.0 mg/L ZnCl2, the exposed group’s hatching began at 7 days instead of at 4 days, and most of the embryos died in the chorion without hatching at 11 and 12 days. Developmental deformities such as abnormal embryogenesis, low hatchability, delayed hatching, and reduction of newly hatched larvae, and a poor survival ratio (mortality ratio of 1.5 and 10 mg/L concentrations compared to control, P < 0.001), were observed during the embryo larval stage due to zinc exposure. Based on these results, we observed that critical and teratogenic effects of ZnCl2 on embryonic development of zebrafish occurred at concentrations greater than 0.5 mg/L. Moreover, our results confirm that the zebrafish embryo teratogenesis assay can be a useful pretest for integrated biological hazard assessment of chemical agents used in industrial production and drug development technologies