The Role of Directly and Indirectly Acting Compounds on Development and Oxidative Stress on Various Early Life Stages

Recent studies in our laboratory comparatively explored toxicity responses associated with oxidative stress (OS) pathways in fathead minnow (Pimephales promelas) and zebrafish (Danio rerio) at early life stages. However, discrepancies between responses of these two common fish models have not been fully investigated across developmental ages. The objective of this study was to examine how OS responses vary: 1. throughout development; 2. between directly acting chemicals and metabolized chemicals; 3. between fathead minnow and zebrafish. Fathead minnow and zebrafish were exposed to R-(-)-carvone or bisphenol-A (BPA). Fish were exposed to control and 40% of the 96-h LC50 value. At 24, 48, 72, and 96 hours post exposure, mortality, hatching rate, and developmental deformity were assessed. Expression of select OS associated genes was measured using qPCR. Results demonstrate that OS responses varied across development in both species, but were also different between both zebrafish and fathead minnow. Furthermore, these responses differed across development between directly acting compounds and metabolized compounds, but only for acute toxic endpoints. In future studies, it will be important to consider bioavailability and uptake in understanding whether adverse outcomes vary across developmental age and between species.