Decabromodiphenyl ether induces the chromosome association disorders of spermatocytes and deformation failures of spermatids in mice

The environmental presence of decabromodiphenyl ether(BDE-209),which is toxic to the male reproductive system,is widespread.The current study investigated its mechanism of toxicity in mice.The results showed,that BDE-209 induced DNA damage,decreased the expression of the promoter of meiosis spermatogenesis-and oogenesis-specific basic helix-loop-helix 1(Sohlh1),meiosis related-factors Lethal(3)malignant brain tumor like 2(L3MBTL2),PIWI-like protein 2(MILI),Cyclin-dependent kinase 2(CDK2),Cyclin A,synaptonemal complex protein 1(SYCP1)and synaptonemal complex protein 3(SYCP3),and caused spermatogenic cell apoptosis,resulting in a decrease in sperm quantity and quality.Furthermore,BDE-209 downregulated the levels of anaphase-promoting complex/cyclosome(APC/C),increased the expression of PIWI-like protein 1(MIWI)in the cytoplasm of elongating spermatids,and decreased the nuclear levels of RING finger protein 8(RNF8),ubiquitinated(ub)-H2A/ub-H2B,and Protamine 1(PRM1)/Protamine 2(PRM2),while increasing H2A/H2B nuclear levels in spermatids.The reproductive toxicity was persistent for 50 days following the withdrawal of BDE-209 exposure.The results suggested that BDE-209 inhibits the initiation of meiosis by decreasing the expression of Sohlh1.Furthermore,the reduced expression of L3MBTL2 inhibited the formation of chromosomal synaptonemal complexes by depressing the expression of meiosis regulators affecting the meiotic progression and also inhibited histone ubiquitination preventing the replacement of histones by protamines,by preventing RNF8 from entering nuclei,which affected the evolution of spermatids into mature sperm.