Study on the genomic imprinting system and plasticity of the male germ cell genome

在这项研究中，我们研究了使用男性生殖细胞通过微受精或核移植技术产生的胚胎、胎儿和动物，以了解它们的遗传和表观遗传变化，这些变化在雄性配子特性的获得中起着最重要的作用。印迹基因在11.5 dpc和12.5 dpc重建的胎儿中的表达分析表明，亲代印迹记忆的消除发生在11.5 dpc，并在12.5 dpc完成。出生后第3.5天对取自卵泡细胞的胎儿的分析表明，到这个阶段父系印迹尚未建立。17日龄的第一波圆形精子参与到子代的正常发育中，表明在第一波精子发生减数分裂前，父本印记已经完成。原代精母细胞（减数分裂前的生精细胞）的染色体在导入MI卵母细胞后进行了正常的减数分裂，并随后支持足月发育。详细的基因表达分析表明，每个印迹基因都有自己的擦除和建立印迹标记的时间表。由原始生殖细胞重建的胚胎在11.5 dpc时的发育能力表明，雄性生殖细胞基因组的全能性可能维持到11.5 dpc或稍早的阶段。

In this study, we examined embryos, fetuses, and animals produced by microinsemination or nuclear transfer techniques using male germ cells to know their genetic and epigenetic changes, which play the most integral part of in the acquisition of the properties of male gametes. Expression analysis of imprinted genes in fetuses reconstructed from primordial germ cells at 11.5 dpc and 12.5 dpc demonstrated that erasure of the parental imprinting memory occurred at 11.5 dpc and has completed by 12.5 dpc. Analysis of fetuses derived from gonocytes at day 3.5 after birth indicated that the paternal imprinting has not yet established by this stage. The first wave round spermatids at 17 days of age participated in normal development into offspring, indicating that the paternal imprinting has completed before meiosis of the first wave of spermatogenesis. The chromosomes of primary spermatocytes, spermatogenic cells before meiosis, underwent normal meiotic divisions after introduced into MI oocytes, and subsequently supported full term development. Detailed gene expression analysis demonstrated that each imprinted gene has each own schedule of erasure and establishment of imprinting marks. The developmental ability of embryos reconstructed from primordial germ cells at 11.5 dpc suggested that the totipotency of the male germ cell genome is probably maintained until 11.5 dpc or a little earlier stage.