Epigenetic reprogramming and chromatin dynamics tin the course of mammalian oocyte development and fertilization

我们试图确定在小鼠核移植过程中，H1foo是否会取代体细胞连接蛋白。移植后不久在供体核中检测到H1foo。此后，H1foo仅限于两细胞期胚胎的染色质。在卵母细胞与表达GFP（绿色荧光蛋白）标记的体细胞连接蛋白H1c的细胞融合后，观察到H1c在供体细胞核中立即释放。此外，我们利用光漂白后荧光恢复（FRAP）发现H1foo比H1c在活细胞中的流动性更强。H1foo更大的流动性可能有助于其快速替换和胚胎染色质结构的不稳定性。这些结果表明，H1c与H1foo的快速替代可能在核重塑中起重要作用。最后，我们使用单个人类卵母细胞的直接rt -巢式PCR鉴定了人类H1foo。综上所述，我们得出结论，供体或精子核中卵母细胞特异性连接蛋白的替换导致染色质组装不稳定，因此它可能有助于胚胎染色质结构的组装，当合子基因激活时，胚胎染色质结构更容易复制和转录。

We tried to determine whether the replacement of somatic linker histones with H1foo occurs during the process of mouse nuclear transfer. H1foo was detected in the donor nucleus soon after transplantation. Thereafter, H1foo was restricted to the chromatin in up to two-cell stage embryos. After fusion of an oocyte with a cell expressing GFP (green fluorescent protein)-tagged somatic linker histone H1c, immediate release of H1c in the donor nucleus was observed. In addition, we found that H1foo is more mobile than H1c in living cells using fluorescence recovery after photobleaching (FRAP). The greater mobility of H1foo may contribute to its rapid replacement and the less stability of an embryonic chromatin structure. These results suggest that rapid replacement of H1c with H1foo may play a significant role in nuclear remodeling. Finally, we identified human H1foo using direct RT-nested PCR of a single human oocyte.Taken together, we conclude that the replacement of oocyte specific linker histones in the donor or sperm nucleus leads to the less stable assembly of chromatin, and thus it might contribute to the assembly of embryonic chromatin structures that are more easily replicated and transcribed when zygotic gene activation occurs.