RNA-SYNTHESIS AND CYTOPLASMIC POLYADENYLATION IN THE ONE-CELL MOUSE EMBRYO
RNA-SYNTHESIS AND CYTOPLASMIC POLYADENYLATION IN THE ONE-CELL MOUSE EMBRYO
复制标题
DOI：
10.1038/295342a0
复制
发表时间：
1982-01-01
期刊：
影响因子：
64.8
通讯作者：
PIKO, L
中科院分区：
文献类型：
--
作者：
CLEGG, KB;PIKO, L
早期哺乳动物胚胎中转录活性的开始时间尚不清楚。RNA合成已被证明发生在小鼠的两个细胞阶段1 - 4和兔子的两到四个细胞阶段5，但受精后的时期已被证明在很大程度上无法进行转录的生化表征，因为早期胚胎对外源前体如3 H-尿苷的渗透性低1 -7。这种困难，以及在单细胞小鼠胚胎的原核中未能检测到RNA聚合酶活性，表明胚胎基因组在第一次分裂后的一段时间内是转录不活跃的。为了进一步研究这个问题，我们现在已经用3 H-腺苷孵育了单细胞原核胚胎，3 H-腺苷的吸收速度比尿苷快1,000倍。可以鉴定出三种标记的RNA种类。主要产物是大的、异质分散的多聚（A）−RNA。高分子量poly（A）+RNA也被大量标记，但这主要是由于先前非多聚腺苷酸化的储存RNA的细胞质多聚腺苷酸化。大量的标记物被掺入到转移RNA的-CCA末端，但也发生一些新的tRNA合成。在单细胞阶段核糖体RNA中没有发现标记，但在两细胞胚胎中成熟rRNA种类的合成是明显的。
The time of onset of transcriptional activity in the early mammalian embryo is unclear. RNA synthesis has been shown to occur at the two-cell stage in the mouse1–4and at the two- to four-cell stage in the rabbit5, but the period immediately following fertilization has proved largely inaccessible to biochemical characterization of transcription because of the low permeability of early embryos to exogenous precursors such as3H-uridine1–7. This difficulty, and the failure to detect RNA polymerase activity in the pronuclei of one-cell mouse embryos8, suggested that the embryonic genome was transcriptionally inactive until some time after the first cleavage. To investigate this issue further, we have now incubated one-cell pronuclear embryos with3H-adenosine, which is taken up about 1,000 times faster than uridine3. Three labelled RNA species could be identified. The major product is large, heterodisperse, poly(A)−RNA. High-molecular-weight poly(A)+RNA is also heavily labelled but this is mostly due to cytoplasmic polyadenylation of previously non-polyadenylated, stored RNA. A significant amount of label is incorporated into the -CCA termini of transfer RNA but some new synthesis of tRNA also takes place. No label was found in ribosomal RNA at the one-cell stage but synthesis of mature rRNA species was evident in the two-cell embryo.