Embryo Developmental And Maternal Toxicity Of Perfluorooctane Sulfonate (PFOS) In The Zebrafish

Increasingly wide attention has been paid to environmental pollution of persistent organic pollutants (POPs) and their effects on ecosystem, and many compounds closely associated with human daily life have been added to the management category of POPs in recent years, and perfluorooctane sulfonate (PFOS) is an important member of them. In the present work, based on the pollution status at home and abroad, zebrafish (Danio rerio) was selected as target organism, and various growth, development and propagation biomarkers of fish were introduced to study the toxicity effects of PFOS on the growth of fish and its potential toxicity mechanism.Results of embryonic exposure experiment showed that 0.5mg/L PFOS could increase the mortality, decrease the hatch rate and heart rate, and induce developmental abnormalities of embryos. perfluorooctanoic acid (PFOA), as another representative substance in the family of fluorinated organic compounds, its acute toxicity was significantly less than PFOS.Results of adult fish exposure experiment showed that the determination of PFOS accumulation in fish body indicated no significant difference between male and female zebrafish, but the resistance of males to PFOS was distinct from that of females, and males were more sensitive than females; After adult zebrafish were exposed to 0, 0.1, 0.5, 1 and 2mg/L PFOS for 7d, results of paraffin section and scanning electron telescope revealed that PFOS could induce obvious lesions of several organs including the gill, intestine, liver and gonad, and the degrees of these lesions had obvious dose-effect relationship, and the lesions were different between males and females; Furthermore, several indexes of oxidative stress enzyme system in the liver of zebrafish were determined: superoxide dismutase (SOD), malondialdehyde (MDA), glutamic pyruvate transaminase (GPT), glutathione reductase (GR) and anti-superoxide anion free radical, and the results showed that when zebrafish were exposed to middle and low concentrations of PFOS (0.5-1mg/L), the activities of SOD, GPT and GR were significantly raised, contents of MDA and anti-superoxide anion free radical tended to increase, but high concentration of PFOS (2mg/L) could depress the enzyme activities of oxidative stress enzyme system and creations of relevant products; the results of real-time PCR showed that the transcription levels of some representative genes in CYP450 enzyme system in males' liver significantly differed from females'; PFOS could also induced expressions of RC and VTG in the liver, which indicated that PFOS was likely to induce edemas and had potential estrogen-like effects; results of cytotoxicity experiment of MCF-7, Hela and HepG2 approved its estrogen-like effects, but its endocrine disrupting effects and potential mechanisms needed further research. The significant differences of these indexes and gene expressions between male and female zebrafish were probably one of the important mechanisms of their different resistence to PFOS.In conclusion, this study synthetically evaluated multiple toxicity effects and potential mechanisms of PFOS in zebrafish by means of embryonic developmental toxicity experiment, adult fish acute expopsure experiment and cell models in vitro, with histopathology and several indexes of oxidative stress enzyme system, CYP450 enzyme system and VTG etc, and provided scientific evidence for evaluation of its ecological safety.