Predicting ZnO nanoparticle and ZnSO4 toxicity from zebrafish embryo gene expression

The potential to replace the early-life-stage toxicity test (ELS) with the gene expression toxicity test in zebrafish (Danio rerio) embryos (gene-DarT) was evaluated. We compared the lowest-observable- effect concentrations (LOECs) for each. For ELS, zebrafish were exposed to ZnO nanoparticles (NPs) and ZnSO4 at 0-0.25 and 0-16 mg/L, respectively, for 28 d. For 48-h gene-DarT tests, expression of potential marker genes (opioid growth factor receptor-like 2 [ogfrl2], cytochrome b5 domain-containing 1 [cyb5d1], and intelectin 2 [intl2] for ZnO NPs and trace amine-associated receptor 10c, CaM kinase-like vesicle-associated, and interferon regulatory factor 2a [irf2a] for ZnSO4) was investigated. The ELS LOECs for ZnO NP and ZnSO4 were 0.016 and 1 mg/L, respectively. Gene-DartT cyb5d1 and irf2a LOECs were 4-16 times lower than ELS LOECs. Gene-DarT ogfrl2 and intl2 and ELS LOECs were similar. Our results suggest the gene-DarT is an effective alternative for predicting ZnO NP and ZnSO4 LOECs.