Study Of The Effects Of Bisphenol A(BPA) On The Development Of Zebrafish Embryos

Bisphenol A(BPA)is a widespread environmental endocrine disruptor(EDCs),which is one of the most widely used organic chemicals in production and life.BPA is widely used in food containers,electronics,sports equipment,food packaging and medical devices.However,the unstable bonding pattern between BPA and plastic matrix makes it a potential threat to the ecological environment and even human health.Although the toxicological studies on BPA are extensive,it is still unclear what effects BPA has on the early development of organisms.In this study,the model organism zebrafish(Danio rerio)was used to evaluate the adverse effects of BPA(5 μg/L and 10 μg/L)on the early development of zebrafish embryos by examining the basal developmental indicators,antioxidant capacity,apoptosis level,inflammatory response and gene transcriptional changes during the embryonic period.The potential mechanisms of BPA toxicity were further investigated in combination with GO functional enrichment analysis and KEGG pathway enrichment analysis.The main findings were as follows:(1)BPA induced apparent developmental toxicity in zebrafish embryos.After 24 h of exposure,zebrafish embryos in the BPA-treated groups(5 μg/L and 10 μg/L)showed a significant decrease in the autonomous movement frequency.Similarly,the heart rate of zebrafish embryos in the BPA-treated group also showed a significant decrease after 48 h of exposure.After 96 h of exposure,the survival rate and hatching rate of zebrafish in the BPA-treated group were significantly reduced.In addition,zebrafish embryos in the BPA-treated group showed a significant delay in hatching at all three time points during the 96-hour stress test.(2)BPA mediates oxidative stress in zebrafish embryos.After 72 h of exposure,the antioxidant enzyme SOD activity and the transcript levels of its coding gene(SOD)were significantly higher in the BPA-treated group than in the control group,while the CAT activity and the transcript levels of its coding gene(CAT)were significantly lower in the BPA-treated group than in the control group.The transcript levels of the related coding genes GPx,Cu/Zn SOD and MnSOD were significantly lower than those of the control group.ROS in situ fluorescence showed that there was an excessive accumulation of ROS in zebrafish embryos in the BPA-treated group.In summary,the above results suggest that BPA exposure seems to cause imbalance of antioxidant capacity and induce oxidative stress in zebrafish embryos.(3)BPA mediates inflammatory responses and apoptosis in zebrafish embryos.In situ fluorescence results showed that there was significant apoptosis in zebrafish embryos continuously exposed to BPA,compared to the control group.Real-time fluorescence quantitative PCR results showed that the transcript levels of key genes involved in apoptosis(p53,gadd45 ba,casp3a and casp3b)and inflammatory response(nfκb,il-6,il-8 and il-1β)were significantly upregulated,indicating that BPA induced apoptosis and inflammatory response in zebrafish embryos.(4)RNA-Seq results showed that 735 differentially expressed genes were present in the BPA-treated group(5 μg/L)compared with the control group,in which multiple biological processes involving oxidative stress,apoptosis and inflammatory response were found to be significantly enriched in GO functional enrichment analysis.Combined with the changes in transcript levels of key genes of inflammatory response in this study,activation of NF-κB signaling pathway seems to be the main pathway of BPA-induced inflammatory response.In addition,the results of KEGG pathway enrichment analysis showed that the P53 signaling pathway,an important pathway involved in regulating apoptosis,was also significantly enriched,suggesting that BPA seems to mediate the development of apoptosis in zebrafish embryonic cells through activation of the P53 signaling pathway.