Gene expression of the mouse reproduced without meiotic division

我们在标准化的实验条件下，从新鲜的或原代培养的具有确定遗传背景的供体细胞的细胞核中克隆小鼠。大多数（99/107）发育至足月的克隆存活且外观正常。在克隆胚胎和胎盘中，印记基因都是从合适的亲本等位基因表达的。然而，在克隆相关的胎盘（总是肥大的）中，几个印记和非印记基因的转录水平显着降低，尽管在相应的胎儿中程度很小。Igf 2和H19的转录物水平（推测为易于克隆诱导的差向刺激的印迹”“基因）在对照范围内。因此，通过核移植进行的克隆不会在数量上扰乱配子发生过程中建立的亲本特异性印记记忆。此外，核转移克隆的表观遗传效应不是随机的，可以追溯到胎盘中表达的特定基因。基因组 ...更多信息 印迹是一种表观遗传机制，它导致父源和母源基因组之间的功能差异，在哺乳动物的发育过程中起着重要作用。印记基因的DNA甲基化模式的阶段特异性变化表明，“它们的印记在原始生殖细胞（PGC）阶段的某个时候被擦除，然后”它们的配子模式在配子发生期间根据个体的性别重新建立。为了确定擦除过程的确切时间和模式，我们分析了胚胎中印记基因的父母来源特异性表达和差异甲基化区域（DMR）的DNA甲基化模式，每个都来自于核移植的单个第-11.5天至第-13.5天的PGC。对-10.5 ~-12.5天PGC的DNA甲基化分析表明，PGC克隆很好地代表了供体PGC的DNA甲基化状态。这些发现提供了强有力的证据，证明基因组印记记忆的擦除过程在第-10.5天到第-11.5天的PGC中进行，并且每个印记基因的时间都得到了精确的控制。少

We cloned mice from the nuclei of fresh or primary cultured donor cells with defined genetic backgrounds under standardized experimental conditions. Most (99/107)clones developing to term were alive and apparently normal. Imprinted genes were all expressed "from appropriate parental alleles in both the cloned embryos and their placentas. However, " significantly reduced transcript levels for several imprinted and non-imprinted genes occurred in clone-associated placentas (which were invariably hypertrophic) although to a "minimal extent in corresponding fetuses. Transcript levels for Igf2 and H19, imprinted" "genes presumed to be prone to cloning-induced epimulation, were within the control range." "Thus, cloning by nuclear transfer does not quantitatively perturb parent-specific imprinting" "memory established during gametogenesis. Moreover, the epigenetic effects of nuclear" "transfer cloning are not stochastic, and can be traced to specific genes expressed in the" placenta. Genomic … More imprinting is an epigenetic mechanism that causes functional differences between "paternal and maternal genomes, and plays an essential role in mammalian development." Stage-specific changes in the DNA methylation patterns of imprinted genes suggest that "their imprints are erased some time during the primordial germ cell (PGC) stage, before" their gametic patterns are re-established during gametogenesis according to the sex of individuals. To define the exact timing and pattern of the erasure "process, we analyzed parental-origin-specific expression of imprinted genes and DNA" "methylation patterns of differentially methylated regions (DMRs) in embryos, each derived" from a single day -11.5 to day -13.5 PGC by nuclear transfer. Analysis of DNA methylation in day -10.5 to -12.5 PGCs demonstrated that PGC clones represented the DNA methylation status of donor PGCs well. These findings provide strong evidence that the erasure process "of genomic imprinting memory proceeds in the day -10.5 to -11.5 PGCs, with the timing" precisely controlled for each imprinted gene. Less