The maternal-to-zygotic transition is a critical window for PFOA-induced disruption of developmental programming
Early embryogenesis is governed by precisely timed gene regulatory programs that coordinate cell fate specification, tissue patterning, and morphogenesis. The maternal-to-zygotic transition (MZT) represents a pivotal developmental milestone during which regulatory control shifts from maternally deposited transcripts to activation of the zygotic genome. Disruption of this transition has the potential to alter developmental trajectories with lasting consequences. Per- and polyfluoroalkyl substances (PFAS), environmentally persistent contaminants, have been linked to developmental abnormalities, yet their impact on core embryonic gene regulatory networks especially with exposure during MZT is not well understood. Using zebrafish ( Danio rerio ), a tractable vertebrate model and New Approach Methodology (NAM), we investigated how PFAS exposure during the MZT alters early developmental programming. Embryos were exposed starting at different times before and within the MZT time window and collected at 24 h post-fertilization (hpf) for transcriptomic analysis. Targeted qRT-PCR revealed dysregulation of genes controlling transcriptional activation, lineage specification, proliferation, and differentiation. Whole-transcriptome RNA sequencing (RNA-seq) further identified widespread perturbations in gene networks governing transcriptional regulation, cell signaling, and embryonic morphogenesis. Temporal analysis revealed that exposure beginning at 3.5 hpf, followed by 8 hpf, corresponding to early zygotic genome activation and near completion of zygotic activation, respectively, resulted in the greatest differential gene expression changes at 24 hpf. Consistent with these early gene regulatory perturbations, larvae exposed starting at 8 hpf also exhibited altered behavior at 5 days post-fertilization. Together, these findings demonstrate that PFAS exposure during MZT disrupts the establishment of embryonic gene regulatory networks, linking environmental toxicant exposure to altered developmental patterning and organismal outcomes. This work underscores the vulnerability of early developmental transitions to environmental perturbation and positions MZT as a critical window of susceptibility during development.