Effect Of Vitritication On DNA Methylation In Donkey Oocytes

Oocyte and embryo vitrification technology is an important part of assisted reproduction technology,various cryopreservation techniques of mammalian oocytes in vitro have gradually matured,and the donkey oocyte freezing and maturation system is incomplete.The donkey has high economic value,but it's breeding ability is low,the study of donkey's oocyte cryopreservation has important economic and academic value.In this study,the methylation of frozen and unfrozen GV,MIand M? Mongolian donkey oocytes was sequenced,and the changes of methylation in frozen and unfrozen donkey oocytes were analyzed.At the same time,we excavate the genes of related to oocyte development and analyze their expression,and the effects of frozen storage on maturation and development of frozen donkey oocytes were analyzed.The results are as follows:1.Frozen GV stage oocytes compared with the unfrozen GV stage oocytes,the degree of methylation after cryopreservation of GV stage oocytes was significantly higher than that of non-frozen GV stage oocytes.The difference was most significant during this period(P<0.05,CpG methyl Percentage comparison:37.5%vs 23.9%);Frozen M? stage oocytes compared with unfrozen MI stage oocytes,the methylation level of cryopreserved MI stage oocytes was higher than that of unfrozen M? stage oocytes,and the difference was significant(P<0.05,CpG methylation percentage comparison:30.3%vs 26.7%);Frozen M? stage oocytes compared with unfrozen M? stage oocytes,the methylation level after cryopreservation was lower than the unfrozen M? stage oocytes,The difference was significant(P<0.05,CpG methylation percentage:23.5%vs 29.8%).2.Num.DMCs=1,num.CpGs=3 and DMC.qvalue=0.01 were selected to identify 1269 differential genes for methylation,of which 692 were up-regulated and 577 were down-regulated.3.The methylation level of GFM1 gene decreased after vitrification and increased in different developmental stages(M? gene expression:15.4862VS3.8498).The methylation level of MRPL15 gene increased after vitrification and decreased significantly at different developmental stages(M? gene expression:0.4076VS2499.73).