The Effect Of Bisphenol A On Meiotic Initiation In Embryonic Chickens

BPA(BisphenolA,BPA)is one of environmental endocrine disruptors(EDC)which have a similar structure to estrogen,and who have weak estrogenic activity.Studies had shown that BPA can enter the body,interfere with the endocrine system,affecting the body’s hormone metabolism,affect the body’s reproductive,developmental,etc.At present,BPA is mainly focused on toxicity research of reproductive toxicology in male and exposed in female pregnancy developmental,while effect low of doses BPA to female developmental advantage are un-know.BPA have a similar structure of estrogen,so it may bond with estrogen receptor play a part in body.In our study,we mainly to research effect of BPA to meiotic in e chicken embryos ovarian tissue for provide theoretical basis inovary meiosis and development.1.BPA were treated in embryonic ovarian cultured in vitro and effect of meiosis in oocytesFrance Sasso eggs were incubated to the embryonic period of 12.5 days(E12.5),and chicken embryos ovarian tissue were cultured in vitro which were treated with 0,0.1,1,10 ug/mL of BPA 3 days respectively to E15.5,nutrient solution were changed per 24 h.The results showed that,10 ug/mL of BPA can significantly increase gene expression of Stra8,Scp3 and Dmcl,and the difference was significantly(P<0.05).10 ug/mL of BPA were used in ovaries cultured in vitro of chicken E10.5,E12.5,E15.5 and E17.5 respectively.BPA can significantly improved Stra8,Scp3 and Dmcl expression at E12.5,E15.5,E17.5 and E18.5 ovarian(P<0.05).Outside,BPA can also significantly reduce the expression of ovary DNA methyltransferase:Dnmtl,Dnmt3a,Dnmt3β(P<0.05).2.The expression of estrogen receptor in BPA-treated embryonic ovarian cultured in vitroE15.5 ovarian tissue in vitro were added E2 and estrogen receptor inhibitors(ICI182780),estrogen receptor(ERa,ERβ,GPR30)were detected by QRT-PCR method expressed in the ovary.The results show that BPA can increase the expression of ERβin the ovarian tissue,but not increase the expression of ERa and GPR30(P>0.05).Therefore,BPA is presumably by binding to ERβ and then play the role of estrogen.3.BPA injected into embryos and the morphology of ovarian tissueFrance Sasso eggs were injected with BPA of 0,0.05,0.5 and 5 mg into the chicken embryo at E12.5 respectively.The results showed that 0.05 mg of BPA can significantly increase the expression of meiotic marker gene Stra8,Scp3 and Dmc1 at E 12.5 of ovaries(P<0.05).0.05 mg of BPA were injected at E10.5,E12.5,E15.5 and E17.5 of embryo in ovaries tissue and continue to hatch E12.5,E15.5,E17.5 and E18.5.The results show that the expression of Stra8,Scp3 and Dmcl significantly increased at E12.5 to E18.5(P<0.05).HE staining results showed that BPA increase thickness of cortical,chromatin condensation darken vesicle and increase in the number of oocytes.And staining by immunofluorescence the results showed that BPA can significantly increased oocyte meiotic division in ovaries,and the positive cells were significant more compared with control(P<0.05).4.The change of Dazl and Stra8 gene methylation in BPA injection embryos and oocytesDazl and Stra8 gene methylation sites were detected in oocytes by BSP sequencing.The results showed that,BPA can induce DNA methylation sites in E12.5 days,Dazl of DNA methylation sites hardly changed but reduce the degree of methylation Stra8 gene,and the difference significantly(P<0.05);BPA can be significantly reduced gene methylation sites and Dazl Stra8 gene at E15.5.BPA process by QRT-PCR detection after,Dazl and Stra8 of mRNA expression levels in E12.5 and E15.5 significantly increased(P<0.05).In summary,BPA have a weak activity of estrogen and which can promote meiosis and primordial follicle development in ovary.By reducing DNA methyltransferase expression and reduced methylation degree Stra8 and Dazl loci,thereby promoting meiotic gene expression and primordial follicle development-related genes.BPA in the body can be combined with ERβ in turn exert estrogenic activity can promote embryo oocyte meiosis,and thus contributing to ovarian primordial follicle formation and development.