The histone variant H3.3 is an important maternal factor in fertilization of oocytes and reprogramming of somatic cell nuclear transfer (SCNT) embryos. As a crucial replacement histone, maternal H3.3 is involved in chromatin remodeling and zygote genome activation. Litte is, however, known about the replacement of H3.3 in the bovine SCNT embryos. In this study, the maternal H3.3 in mature ooplasm was labeled with HA tag and the donor cells H3.3 was labeled with Flag tag, in order to observe the replacement of H3.3 in the bovine SCNT embryos. Meanwhile, maternal H3.3 knockdown was performed by microinjecting two different interfering fragments before nucleus transfer. It was showed that the dynamic replacement between maternal- and donor nucleus-derived H3.3 was detected after SCNT. And it could be observed that the blastocyst development rate of the cloned embryos decreased from 22.3% to 8.2-10.3% (P < 0.05), the expression of Pou5f1 and Sox2 was down-regulated and the level of H3K9me3 was increased in the interfered embryos. In summary, H3.3 replacement impacted on the process of reprogramming, including embryonic development potential, activation of pluripotency genes and epigenetic modification in bovine SCNT embryos.

中文翻译：

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H3.3 的动态替换影响早期牛 SCNT 胚胎的核重编程

组蛋白变体 H3.3 是卵母细胞受精和体细胞核移植 (SCNT) 胚胎重编程的重要母体因素。作为重要的替代组蛋白，母体 H3.3 参与染色质重塑和合子基因组激活。然而，Litte 知道牛 SCNT 胚胎中 H3.3 的替代。本研究将成熟卵质中的母体H3.3用HA标签标记，供体细胞H3.3用Flag标签标记，以观察牛SCNT胚胎中H3.3的置换情况。同时，母体 H3.3 敲低是通过在细胞核转移前显微注射两种不同的干扰片段来进行的。结果表明，在SCNT后检测到母体和供体核来源的H3.3之间的动态置换。并且可以观察到克隆胚胎的囊胚发育率从22.3%下降到8.2-10.3%（P < 0.05），Pou5f1和Sox2的表达下调，H3K9me3水平升高。 . 总之，H3.3 替代影响了牛 SCNT 胚胎的重编程过程，包括胚胎发育潜力、多能性基因的激活和表观遗传修饰。