New insights into triazole fungicide-caused hematopoietic abnormality in zebrafish based on GRα screening developmental toxicity

Triazole fungicides (TFs) are known to be common environmental contaminants that can be toxic to aquatic animals, but their developmental toxicity is not fully understood. To address this gap, we first used a glucocorticoid receptor α (GRα)-mediated dual luciferase reporter gene system to explore the possible development toxicity of ten TFs and found that flusilazole (FLU) exhibited stronger agonistic activity against GRα. Subsequent transcriptome sequencing showed that FLU exposure affected GRα activation and hematopoiesis associated with a variety of biological processes, including responses to corticosteroid release, embryonic hematopoiesis, erythroid differentiation, and the development of hematopoietic or lymphoid organs. Furthermore, based on in situ hybridization and staining techniques, we clarified that FLU decreased the expression of the primitive hematopoietic marker genes gata1 and pu.1. and caused the defects in the posterior blood island (PBI), thereby impacting intermediate hematopoietic processes. Also, FLU significantly reduced the expression of the crucial hematopoietic gene cmyb and disrupted the production of erythrocytes and bone marrow cells during definitive hematopoiesis. Consistently, we found that FLU induced lesions in the kidney, a hematopoietic organ, including the infiltration of inflammatory cells, tubular collapse, reduced tubular filtration area, and interstitial hydronephrosis. We also found that FLU increased aberrant red blood cells in the peripheral blood of zebrafish. These findings provide new insights into the developmental toxicity and ecotoxicological risk of TFs.