Determination of nanoparticle toxicity to larval zebrafish (Danio rerio) by assessment of gene expression

In this study, the dose-response experiments were performed to determine lethal and sublethal concentrations of carbon 60 (C60), titanium dioxide (TiO2), copper (Cu), and silver (Ag) nanoparticles in zebrafish (Danio rerio) larvae by developing a new nanoparticle test system. Also, the changes in expression of the gene encoding metallothienin-2 protein were analyzed with SYBR Green I method through Real-Time PCR analysis. Repeatable test results were obtained with the newly developed test system at three different time periods and LC50 values for Ag, Cu, and TiO2 NPs were calculated as 0.27, 0.65 and 897 mg/L, respectively. As a result of the MT-2 gene expression analysis performed with different Hg2+ concentrations, it was determined that Hg2+ caused an increase in MT-2 gene expression ten times (89%) higher in comparison with the control group. According to the results of gene expression of C60 and TiO2-NPs associated with Hg2+, C60 and TiO2-NPs decreased the toxicity of Hg2+ significantly. It was determined that gene expression of Cu2+ was higher three times than Cu-NPs in the comparative toxicity experiments of Cu2+ and Cu-NPs. Furthermore, the toxicity of Cu-NPs decreased in water containing EDTA while increased in hard water (as mg/L CaCO3).