Ribosomal ribonucleic acid is transcribed at the 4-cell stage in in vitro-produced bovine embryos.
Ribosomal ribonucleic acid is transcribed at the 4-cell stage in in vitro-produced bovine embryos.
复制标题
核糖体核糖核酸在体外产生的牛胚胎的 4 细胞阶段转录。
作者：
D. Viuff;P. Hyttel;B. Avery;G. Vajta;T. Greve;H. Callesen;P. Thomsen
核糖体RNA，rRNA基因，和银染核仁蛋白可视化在体外生产的牛胚胎从2-细胞阶段的囊胚使用顺序荧光原位杂交（FISH）和银染程序。在FISH中，通过比较RNase和非RNase处理的胚胎，将rRNA与rRNA基因的信号区分开来。RNase和非RNase处理的2-细胞胚胎发现多达10个小簇的异硫氰酸荧光素（FITC）标记间期核。RNase处理的4-细胞胚胎显示与2-细胞胚胎相同的FITC模式。相比之下，在非RNase处理的4细胞胚胎中，簇更大，包括许多小斑点。在2-细胞和4-细胞胚胎中，几乎所有的FITC标记的簇与银染斑点共定位。在RNase处理的8- 16-细胞胚胎中，多达10个FITC标记簇被组织为一个或多个围绕中心微弱但均匀标记区域的大斑点。非RNase处理的8- 16细胞胚胎显示出类似的复合物，但中心区域由小的标记点组成。在8至16细胞胚胎中，所有FITC标记的簇再次与银染色区域共定位。在囊胚内，银染色共定位1-6个大的FITC标记簇。在RNase处理的囊胚中，FITC标记通常位于银染区域的边缘，而在非RNase处理的囊胚中，FITC标记完全覆盖银染区域。总之，在第二细胞周期的体外产生的牛胚胎中，rRNA基因和银染核仁蛋白之间存在密切联系，即，2细胞期;第一个rRNA在第三个细胞周期中被转录，在第四个细胞周期中，功能性核仁的分子组成被确定。
Ribosomal RNA, rRNA genes, and silver-staining nucleolar proteins were visualized in in vitro-produced bovine embryos from the 2-cell stage to the blastocyst using a sequential fluorescent in situ hybridization (FISH) and a silver-staining procedure. At FISH, the rRNA was differentiated from the signal of the rRNA genes through comparison of RNase- and non-RNase-treated embryos. Both RNase- and non-RNase-treated 2-cell embryos revealed up to 10 small clusters of fluorescein isothiocynate (FITC) labeling in interphase nuclei. The RNase-treated 4-cell embryos displayed the same FITC pattern as the 2-cell embryos. In the non-RNase-treated 4-cell embryos, in contrast, the clusters were larger and included numerous small spots. In 2-cell as well as 4-cell embryos, almost all FITC-labeled clusters colocalized with silver-stained spots. In the RNase-treated 8- to 16-cell embryos, up to 10 clusters of FITC labeling were organized as one or more large spots surrounding a central faint but homogeneously labeled area. The non-RNase-treated 8- to 16-cell embryos displayed similar complexes, but the central areas consisted of small labeled spots. In 8- to 16-cell embryos, all FITC-labeled clusters were again colocalized with silver-stained areas. In the blastocysts, 1-6 big clusters of FITC labeling colocalized with silver staining. In the RNase-treated blastocysts, the FITC labeling was typically located at the edges of the silver-stained areas, whereas in the non-RNase-treated blastocysts, the FITC labeling totally covered the silver-stained areas. In conclusion, there is a close association between the rRNA genes and silver-staining nucleolar proteins in in vitro-produced bovine embryos from the second cell cycle, i.e., the 2-cell stage; the first rRNA is apparently transcribed during the third cell cycle, and during the fourth cell cycle the molecular composition of functional nucleoli is established.