Environmental relevant herbicide prometryn induces developmental toxicity in the early life stages of marine medaka (Oryzias melastigma) and its potential mechanism

Triazine herbicides have been widely detected in marine environments because of their extensive usage in agriculture, but their impact on marine organisms is unclear. In this study, marine medaka (Oryzias melastigma) embryos were exposed to 0, 1, 10, 100, and 1000 mu g/L prometryn, one of the most detected triazine herbicides, to investigate its potential effects. The results showed that 1, 10, 100, and 1000 mu g/L prometryn not only induced yolk sac shrinkage and heart malformations, but also significantly delayed the hatching time and increased the heart rate and hatching failure rate of embryos. Moreover, 1, 10, 100, and 1000 mu g/L prometryn caused obvious malformations and decreased the body length of the newly hatched larvae. After 21 d of exposure, increased larval death rate, decreased body length and width, and higher lipid accumulation were observed in the larvae from all prometryn groups. Furthermore, prometryn exposure upregulated the expression levels of cardiac development-related genes GATA, COX, ATPase, SmyD1, EPO, FGF8, NKX2, and BMP4 in the larvae. Transcriptome analysis revealed that 10 mu g/L prometryn upregulated 604 genes, and the topmost pathways of differentially expressed genes were the complement and coagulation cascades and AMPK signaling pathways. qPCR results confirmed that prometryn exposure significantly increased the expression levels of the complement and coagulation cascade genes f2, f5, c3, and c5. This study demonstrated that environmentally relevant concentrations of prometryn induced significant toxicity in the early life stages of marine medaka. Therefore, the health risks of herbicides to marine organisms are of great concern.