Jeffries, Marlo2025-08-082025-08-082025-07-25https://repository.tcu.edu/handle/116099117/67412Environmental contaminants can disrupt immune function in fish, increasing disease susceptibility and posing significant ecological and economic risks. However, a standardized assay for screening immunotoxicity in North American fish species has yet to be developed. This study aimed to adapt the existing fathead minnow (Pimephales promelas) larval growth and survival test to include an assessment of innate immune function using transcriptomic biomarkers following a partial tail injury. Differential gene expression analysis via RNA-seq identified 680 significantly regulated genes, of which a substantial portion were linked to immune and inflammatory processes. Key biomarkers—gfap, lamc1, nrp1a, tnfrsf1a, il1β, cox2, and caspa—were validated by qPCR in biological replicates, confirming consistent upregulation after tail injury. To assess assay sensitivity, larvae were exposed to the known immunosuppressant naproxen. While gene expression responses varied, tnfrsf1a, caspa, and cox2 showed trends consistent with immunosuppressive activity. These results demonstrate the potential for using transcriptomic biomarkers in fathead minnows to detect innate immune modulation by chemical stressors and establish a foundation for a standardized immunotoxicity screening assay. Future work should refine biomarker panels and apply the assay to environmentally relevant contaminants.Format: OnlineenBiologyToxicologyImmunologyText