牛核移植胚胎中IGF2/H19基因簇父源印记控制区甲基化模式研究

Methylating Pattern of IGF2/H19 Imprinting Cluster in Clone Embryos

为了揭示牛核移植胚胎异常甲基化模式,选择配子期、S期、2-cell、8-cell和桑葚胚5个发育阶段的早期核移植胚胎作为试验组,以相应阶段的体外受精胚胎(IVF)作为对照,对核移植胚胎中呈父源印记的IGF2/H19基因簇ICR区进行了BSP测序。结果表明:SCNT的父源基因在S期之前发生了主动去甲基化,伴随着DNA复制的开始,又发生了被动去甲基化。SCNT胚胎父源基因与IVF胚的甲基化重建能力相当;筛选了1个去甲基化抑制机制的易感位点,H19的转录起始点前468 bp开始的262 bp序列中的4号甲基化位点。

In order to study the methylating pattern of bovine clone embryos,early cloned embryos at five development stages（gamophase,S phase,2-cell,8-cell and morula）were selected to study the methylating pattern of IGF2/H19 imprinting cluster by Bisulfite sequencing PCR（BSP）. The results showed that actively demethylation of paternal germline was very weak before cleavage in early cloned embryos,and the ability of de novo methylation after 8-cell was the same as IVF embryos. One CPG Positions were found,which were prone to de novo methylation,they were respectively the fourth CPG Position located in a 262 bp region 468 bp upstream of the H19 transcriptional start.