Nuclear distribution of Death-associated protein 6 (Daxx) was studied using fluorescent and electron microscopy in mouse embryos at different stages of development in vivo, from zygote to morula. Daxx was found in association with transcriptionally silent chromatin predominantly with a heterochromatin rim surrounding the nucleolus precursor bodies (NPBs) at all stages studied. At the zygote stage, Daxx was detected only at the periphery of NPBs both in male and female pronuclei. At the late two-cell stage, Daxx was localized not only in the heterochromatin rim at the periphery of NPBs but also in heterochromatin zones not associated with NPBs. At the morula stage, a diffuse distribution of Daxx prevailed. Scarce Daxx-positive zones were detected only in some embryos at the nucleolar periphery. Thus, Daxx is noticeably redistributed during mouse embryo cleavage, and the most conspicuous areas of Daxx concentration are observed at the end of two-cell stage. Daxx is found colocalized with the chromatin-remodeling protein ATRX exclusively in two-cell embryos, but the heterochromatin areas containing either Daxx or ATRX individually are also observed at this stage. However, most zones containing both Daxx and ATRX demonstrated a low FRET-efficiency. This suggest that two molecules are not approached sufficiently close for molecular interactions to occur. Our data suggests that Daxx may function without cooperation with ATRX at least at some stages of early mouse development.

中文翻译：

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DAXX蛋白在小鼠早期胚胎细胞核中的分布动态。

使用荧光和电子显微镜研究了从受精卵到桑ula的体内不同发育阶段的小鼠胚胎中死亡相关蛋白6（Daxx）的核分布。在研究的所有阶段，发现Daxx与转录沉默染色质相关，主要与围绕核仁前体（NPB）的异染色质边缘相关。在合子阶段，Daxx仅在雄性和雌性原核的NPBs外围被检测到。在两细胞晚期，Daxx不仅位于NPBs外围的异染色质边缘，而且位于与NPB不相关的异染色质区域。在桑ula虫阶段，Daxx的分布很普遍。仅在核仁周围的某些胚胎中检测到稀缺的Daxx阳性区。从而，Daxx在小鼠胚胎切割过程中明显重新分布，并且在两细胞阶段结束时观察到最明显的Daxx浓度区域。发现Daxx仅与染色质重塑蛋白ATRX共定位于两细胞胚胎中，但在此阶段还观察到分别含有Daxx或ATRX的异染色质区域。但是，大多数同时包含Daxx和ATRX的区域都表现出较低的FRET效率。这表明没有足够接近地接近两个分子以发生分子相互作用。我们的数据表明，至少在早期小鼠发育的某些阶段，Daxx可能在不与ATRX合作的情况下起作用。发现Daxx仅与染色质重塑蛋白ATRX共定位于两细胞胚胎中，但在此阶段还观察到分别含有Daxx或ATRX的异染色质区域。但是，大多数同时包含Daxx和ATRX的区域都表现出较低的FRET效率。这表明没有足够接近地接近两个分子以发生分子相互作用。我们的数据表明，至少在早期小鼠发育的某些阶段，Daxx可能在不与ATRX合作的情况下起作用。发现Daxx仅与染色质重塑蛋白ATRX共定位于两个细胞的胚胎中，但在此阶段还观察到了分别含有Daxx或ATRX的异染色质区域。但是，大多数同时包含Daxx和ATRX的区域都表现出较低的FRET效率。这表明没有足够接近地接近两个分子以发生分子相互作用。我们的数据表明，至少在早期小鼠发育的某些阶段，Daxx可能在不与ATRX合作的情况下起作用。