Perfluorooctane sulfonic acid (PFOS) is a persistent chemical previously used in stain-resistant products and firefighting foam. The extensive usage has enabled widespread exposure that has been shown to induce oxidative stress via enhanced generation of reactive oxygen species (ROS) and is linked to numerous negative health outcomes. Early life stages of development are especially vulnerable to PFOS and ROS. This study aims to characterize the spatial distribution of ROS induced by PFOS in embryonic zebrafish at different developmental stages. 

Embryos from a zebrafish strain lacking pigment (mitfab692/b692) were exposed to 0 (0.01% DMSO), 1, 2, and 4 μM PFOS beginning at 3 hours post-fertilization (hpf); treatments were refreshed daily. At 24, 48, or 72 hpf, 96 embryos were washed then incubated in 10 μM CellROX Green for 1 hour, fixed in 4% paraformaldehyde, then stored in 25% glycerol. Imaging was performed using an EVOS FL Auto microscope at 4x magnification under a GFP filter. Fluorescence, indicative of ROS, was assessed via whole body tracing and heat maps generated using ImageJ software.

Results illustrate increased fluorescence intensity in the PFOS-exposed groups compared to the control, with higher fluorescence intensity around the head. With increasing age, differences in fluorescence between the PFOS-exposed and control groups decreased, suggesting maturation of the antioxidant defense responses. These findings show increased ROS detection after exposure to PFOS and provide a baseline for larval zebrafish response to oxidative stress. Future research will probe at the implications of this oxidative stress on metabolic health and development.