Reproductive toxicity effects and mechanisms of perfluorobutane sulfonate on the Clitellum in Eisenia fetida: Insights from histopathology, multi-omics and biomarker analyses

Perfluorobutane sulfonate (PFBS) persistently leaks into soils via landfill leachates and wastewater effluents due to inefficient removal, yet mechanisms underlying its reproductive toxicity in soil fauna remain poorly understood. This study demonstrates PFBS-induced reproductive toxicity in Eisenia fetida following 28-day exposure (0.1, 1, 10 mg/kg), manifested by reduced cocoon number, size, and aspect ratios, decreased sperm counts in seminal vesicle, chromatin depletion of spermathecae, and structural damage of sperm cyst in the clitellum. Transcriptomics revealed WNT, protein digestion/absorption, and NF-κB pathways dysregulated across all levels, while oxytocin and oocyte meiosis pathway altered at 10 mg/kg PFBS. Besides, metabolomics revealed concerted collapse of energy metabolism, amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism in the clitellum. Expression level of ATP6, TRIAP1, CYP450, TCTP, and CCF-1 was up-regulated to counter environmental stress, while the biphasic responses of ANN indicated the limited regulating ability. Additionally, PFBS triggered oxidative stress in the clitellum, significantly altering CAT activity, POD activity, GST activity, and MDA levels (P＜ 0.05). These results suggest that PFBS may disrupt reproduction through DNA repair failure, metabolic network sabotage, and redox imbalance, providing data support for revealing the reproductive toxicity mechanism of PFBS.