Stereoselective Reproductive and Intergenerational Toxicity of Prothioconazole in Female Zebrafish: Concurrent Ovarian Cytotoxicity and Endocrine Disruption

Prothioconazole (PTCZ) is a chiral fungicide generally assessed as a racemate, potentially masking enantiomer-specific hazards. Adult female zebrafish were chronically exposed to environmentally relevant concentrations of racemic PTCZ, R-(-)-PTCZ, or S-(+)-PTCZ. S-(+)-PTCZ caused the strongest reproductive and intergenerational toxicity, whereas Rac-PTCZ showed intermediate effects and R-(-)-PTCZ elicited weaker responses. S-(+)-PTCZ reduced fecundity and GSI, disrupted follicle development, increased follicular atresia, and impaired F1 hatching, survival, and morphology. Ovarian injury was accompanied by increased γ-H2AX, PARP, Caspase-3, and TUNEL staining, mitochondrial abnormalities, ATP depletion, and altered NAD+/NADH status. S-(+)-PTCZ also perturbed HPG-axis end points, including FSH, LH, E2, VTG, and steroidogenesis-related transcripts. These findings reveal pronounced stereoselective reproductive hazards of PTCZ under the tested exposure conditions and support enantiomer-specific ecological risk assessment.