Juvenile exposure to imazalil disrupts epigenetic and transcriptomic regulation of hepatic energy metabolism in Xenopus tropicalis.

The extensive use of agricultural pesticides has led to widespread environmental contamination, raising concerns about their adverse biological effects. The fungicide imazalil is known to cause endocrine-disrupting and hepatotoxic effects in vertebrates, but potential underlying epigenetic mechanisms remain poorly understood. In this multiomics study, we investigated hepatic epigenetic and transcriptomic responses in juvenile Xenopus tropicalis (6.5 weeks post-metamorphosis) following two weeks exposure to an environmentally relevant concentration of imazalil (12.3 μg/L). Thousands of differentially methylated cytosines (DMCs) were identified in both sexes, whereas significant gene expression changes were primarily detected in males. The genomic locations of DMCs were largely sex-specific, with only 162 sites shared between males and females. Gene Set Enrichment Analysis indicated disruption of energy metabolism in both sexes, while sex-specific responses included downregulation of cell cycle and chromatin organization pathways in males and upregulation of immune-related pathways in females. Integration of methylation and expression data identified 8083 strong correlations involving 2303 CpGs, including individual CpG sites whose methylation levels were linked to the expression of multiple functionally related genes enriched for cell cycle regulation and chromatin organization pathways. Together, these results suggest coordinated, potentially trans-regulatory epigenetic control of hepatic transcriptional networks that may mediate imazalil-induced hepatotoxic effects. The observed sex-specific responses further suggest that disruption of sex-hormone signaling may contribute to differential sensitivity to exposure. Overall, this study highlights the toxicogenomic effects of imazalil and underscores the importance of considering epigenetic mechanisms in future chemical risk assessment frameworks, with implications for both amphibian health and human environmental exposure.