Chlorophenols suppress gametogenesis by disrupting sex hormone signaling through DNA methylation in zebrafish

Chlorophenols (CPs) are toxic pollutants widely present in the water environment. Yet their specific influence on gametogenesis remains unclear. This study investigated the impact of 2,4-dichlorophenol and pentachlorophenol on the gametogenesis of zebrafish. Results showed reduced egg production and sperm density in CP-exposed zebrafish, with an increase in the proportion of early germ cells and a decrease in mature germ cells. Additionally, the expression of gametogenesis-related genes (nanos3, ccnd1, dmc1) was upregulated, together confirming CPs suppress gametogenesis. The study also assessed the effects of CPs on sex hormone signaling, revealing altered ratios of estradiol to 11-ketotestosterone and changed expression of hormone receptors (esrs and ar). Besides, the hypothalamic-pituitary-gonadal axis genes showed significantly change, indicating the disorder of sex hormone signaling. Moreover, CPs increased DNA methylation levels in gonads, especially at CpG sites in the ar promoter, which negatively correlated with ar expression. Furthermore, elevated DNA methyltransferase (dnmts) expression was observed, and there was a significant interaction between CPs and Dnmts, suggesting CPs influence DNA methylation pathways. Overall, CPs inhibit gametogenesis by disrupting hormone signaling through DNA methylation. This study provides a new perspective on the toxic mechanisms and the risks posed by CPs to aquatic organisms.