Transcriptome Analysis of Thiram-Treated Zebrafish (Danio rerio) Embryos Reveals Disruption of Reproduction Signaling Pathways

SIMPLE SUMMARY: Thiram is a widely used fungicide, yet studies have shown that it has hazardous effects on animals, including fish. We performed developmental and transcriptome analyses of thiram-exposed zebrafish embryos to further understand thiram toxicity. Thiram-exposed embryos exhibited several developmental abnormalities. Transcriptome analysis revealed 1754 differentially expressed genes associated with thiram exposure when compared to controls. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of thiram-treated samples highlighted reproduction-related pathways. The current findings shed light on the molecular mechanisms through which thiram exerts developmental and reproductive toxicity in zebrafish. ABSTRACT: Thiram, a dithiocarbamate fungicide, is used for the treatment of various fungal infections affecting crops and ornamentals. However, thiram-associated toxicity has been reported in animals, including fish, and the underlying molecular mechanisms are unclear. Herein, we employed zebrafish (ZF) to gain further insights into thiram toxicity-associated molecular mechanisms. We studied developmental abnormalities and performed whole-transcriptome analysis of ZF embryos exposed to thiram for 96 h. Embryos exposed to 4.0 μg/L thiram exhibited several phenotypic abnormalities, including bradycardia, spinal curvature, hatching arrest, and growth retardation. Whole-transcriptome analysis revealed 1754 differentially expressed genes (DEGs), with 512 upregulated and 1242 downregulated DEGs. The majority of biological processes affected by thiram were metabolic. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis yielded terms related to reproduction, such as steroid biosynthesis and steroid hormone biosynthesis. Quantitative real-time polymerase chain reaction validation results were in line with sequencing data for ten DEGs. The study results improve our current understanding of the effects of thiram exposure in ZF.