Toxic effects of combined exposure of tritiated water and genistein on the growth and development of zebrafish and its mechanism

Water pollution and control are important issues of our lasting concern. Environmental media often contains a variety of compounds. Tritium is widely present in nature due to human activities. As an endocrine disruptor, genistein is widely found in water body. Will it cause damage when combined with tritiated water and genistein? In this study, Zebrafish embryos were randomly divided into 4 groups: blank control group (simple E3 medium), tritiated water exposure group (tritiated water with a final concentration of 3.7*10 2 Bq/mL in the medium), and genistein exposure group (the final concentration of 1.4 mg/L genistein in the medium) and the combined exposure group of tritiated water and genistein (3.7*10 2 Bq/mL tritium water +1.4 mg/L genistein). The results show that tritiated water with 3.7*10 2 Bq/ml exposure alone did not affect the development of zebrafish embryos. However, the survival rate, hatching rate and heart rate of zebrafish larvae decreased combined exposure with genistein, and the abnormality rate and apoptotic cells in the embryos and the level of oxidative stress increased. The results of RNA sequencing showed that the combined exposure of tritiated water and genistein affected the gene expression of zebrafish embryos. Differential genes were mainly enriched in many pathways, such as p53 signaling pathway, steroid hormone biosynthesis, PPAR signaling pathway, metabolism of xenobiotics by cytochrome P450. The results of qRT-PCR and gene knockout experiment showed that cyp19a1b gene may plays an important role in the toxic effects of combined exposure.