Effects of phenanthrene,pyrene and benzo(a)pyrene individual exposure and co-exposure with α-naphthoflavone on the embryonic development of marine medaka(Oryzias melastigma)

In order to understand the developmental effects and mode of actions of marine fish embryos exposed to three-to five-ring PAH,the ovo EROD activity,heart elongation,hatch rate and heartbeat were measured after the individual exposure of phenanthrene(Phe),pyrene(Py) and benzo(a)pyrene(BaP) and co-exposure each of them with α-naphthoflavone(ANF) for marine medaka(Oryzias melastigma) embryos.Results showed that the rank order in the potency for causing ovo EROD activity induction in marine medaka embryos was BaPPyPhe.The relationships between EROD induction and embryo development deformity in each individual exposure of Phe,Py and BaP were very complex,a significant correlated with ovo EROD and deformity index was observed only in Phe(r=0.95,p=0.015).Embryos co-exposed to 100 μg/L ANF with each of each of Phe,Py and BaP were increased in the severity of deformities and were decreased in the hatch rates compared with embryos exposed to PAH individual.The combination effects of each PAH with ANF showed potential synergistic effects.These results demonstrated that there may be different mode of actions on the developmental toxicity effects of marine medaka embryos exposed to three-to five-ring PAH,CYP1A activity inhibited by ANF would not effectively alleviate the embryonic development toxicity on marine medada exposed to PAH.There may be a potential synergistic effect on the toxicity in marine fish embryos co-exposed to CYP1A inhibitor and PAH-type CYP1A inducer,and the current PAH mixture risk assessment model may underestimate their toxicity,particularly of mixtures containing both CYP1A inducers and inhibitors.Heart deformities found to be the most sensitive endpoint in early life stage of marine medaka were recommended as a biomarker to indicate the pollution of PAHs or oil spill in field study.