Transcriptomic effects of endocrine disruptors in zebrafish embryos

The identification of endocrine disruptive properties of chemicals certain to enter the aquatic environment relies on toxicity tests with fish, assessing adverse effects on reproduction and sexual development. The demand for quick, reliable endocrine disruption (ED) assays favored the use of fish embryos as alternative test organisms. We investigated the application of a transcriptomics-based assay for estrogenic and anti-androgenic chemicals with zebrafish embryos. Two reference compounds, 17a-ethinylestradiol and flutamide, were tested to evaluate the effects on development and the transcriptome after 48h-exposures. Comparison of the transcriptome response with other estrogenic and anti-androgenic compounds (genistein, bisphenol A, methylparaben, linuron, prochloraz, propanil) showed commonalities and differences in regulated pathways, enabling us to classify the estrogenic and anti-androgenic potencies. This demonstrates that different mechanism of ED can be assessed already in fish embryos. Newly fertilized embryos (<2hpf) were exposed for 48 hours to 0.65mg/l (EC10) and 0.8mg/l (EC20) 17-alpha ethinylestradiol (EE2), 1.2mg/l (EC10) and 1.4mg/l (EC20) flutamide, 8 mg/l (EC10)and 8.5mg/l (EC20) bisphenol A(BPA), 0.8 mg/l (EC10) and 1.1mg/l (EC20) propanil, 19.8mg/l (EC10) and 24.4mg/l (EC20) methylparaben, 1.2 mg/l (EC10) and 1.3mg/l (EC20) linuron as well as to 1.7mg/l (EC10) and 2 mg/l (EC20) prochloraz. Water controls were included in all studies and acetone solvent controls were applied when indicated (AC). For each study, four replicates (a,b,c,d) were performed per condition, each consisting of 24 pooled embryos.