Morphometric Characteristics and Time to Hatch as Efficacious Indicators for Potential Nanotoxicity Assay in Zebrafish

Although the effects of nano-sized titania (nTiO2) on hatching events (change in hatching time and total hatching) in zebrafish have been reported, additional consequences of nTiO2 exposure (i.e., the effects of nTiO2-induced changes in hatching events and morphometric parameters on embryo-larvae development and survivability) have not been reported. To address this knowledge gap, embryos 4 h postfertilization were exposed to nTiO2 (0, 0.01, 10, and 1000 μg/mL) for 220 h. Hatching rate (58, 82, and 106 h postexposure [hpe]), survival rate (8 times from 34 to 202 hpe), and 21 morphometric characteristics (8 times from 34 to 202 hpe) were recorded. Total hatching (rate at 106 hpe) was significantly and positively correlated to survival rate, but there was no direct association between nTiO2-induced change in hatching time (hatching rate at 58 and 82 hpe) and survival rate. At 58, 82, and 106 hpe, morphometric characteristics were significantly correlated to hatching rate, suggesting that the nTiO2-induced change in hatching time can affect larval development. The morphometric characteristics that were associated with change in hatching time were also significantly correlated to survival rate, suggesting an indirect significant influence of the nTiO2-induced change in hatching time on survivability. These results show a significant influence of nTiO2-induced change in hatching events on zebrafish embryo-larvae development and survivability. They also show that morphometric maldevelopments can predict later-in-life consequences (survivability) of an embryonic exposure to nTiO2. This suggests that zebrafish can be sensitive biological predictors of nTiO2 acute toxicity