Effects Of Bisphenolaand It's Substitutes Ondevelopment,Reproduction Andtranscription Of Related Genes In Daphniamagna

For a long time,most of the environmental toxicity and risk assessment of the bisphenols are based on vertebrate tests,but the research on the toxic effect and mechanism of these pollutants on low trophic level organisms is still limited.In this study,Daphnia magna(D.magna)was chosen as a model animal,and according to the standard test procedure for the reproductive toxicity test of Daphnia magna stipulated by OECD,estradiol(E2)was used as the positive control to evaluate the developmental and reproductive toxicity of the typical bisphenols,bisphenol A(BPA)and it's 3 substitutes bisphenol AF(BPAF),bisphenol F(BPF)and bisphenol S(BPS).The work and main results of this study are as follows:1.For the positive control,exposure to 5000 n M E2 to Daphnia magna for 21 days caused a significant lethal effect,and significantly reduced the survival rate to 71%,inhibited the early body growth and molting behavior,increased the number of offspring,but the maternal exposure of E2 did not affect the growth and development of F1 generation.The other lower exposure concentrations(5,50 and 500 n M)did not have any above effects.Fluorescence quantitative PCR results showed that,5000 n M E2 exposure significantly down-regulated the transcription of the genes cytochrome P450 18a1(cyp18a1)and hormone receptor 3(hr3),suggesting that E2 might cause developmental and reproductive toxicity by interfering with the metabolism of ecdysone in Daphnia magna.2.The 48-h acute toxicity test showed that the 48 h median lethal concentrations(LC50)of BPA and its substitutes BPAF,BPF and BPS were 7.99,2.83,9.75 and 105.60mg/L,respectively.These results demonstrated that the toxicity of substitute BPAF was stronger than that of BPA;the toxicity of BPF is similar to that of BPA,but slightly less than that of BPA;the toxicity of BPS is the smallest.Based on the above results,a further21-day chronic exposure test of BPA and BPAF were performed.Consistent with the results of positive control E2,both BPA and BPAF had significant lethal effect,developmental inhibition and reproductive promotion effect on D.magna.Exposure to5000 n M BPA or 500 n M BPAF significantly reduced survival of Daphnia magna to 75%and 31%,respectively;significantly decreased the swim speed of F0 generation;improved the number of offspring of F0 generation but inhibited the body growth and decreased the swim speed of F1 generation.In addition,exposure to 500 n M BPAF significantly inhibited the molting behavior and body growth of F0 generation,while exposure to 5000 n M BPA had no significant effects.These results indicated that the toxicity of BPAF was stronger than that of BPA in the 21-day chronic exposure test,which was consistent with the results of the 48-h acute tests.Fluorescence quantitative PCR results showed that exposure to 5000 n M BPA significantly down-regulated the transcription of cytochrome P450 gene 314(cytochrome P450 314,cyp314)which was related to the synthesis of ecdysone in Daphnia magna while exposure to 500 n M BPAF significantly down-regulated the transcription of cyp314 and significantly up-regulated the transcription of cyp18a1.These results suggested that the developmental and reproductive toxicity of E2,BPA and BPAF might be related to the interference of these pollutants with ecdysone synthesis and metabolism in Daphnia magna.