Wakefield L, Ackerman E, Gurdon J B
Dev Biol. 1983 Feb;95(2):468-75. doi: 10.1016/0012-1606(83)90048-9.
Previous work has shown that nuclei of cultured cells or erythrocytes are transcriptionally activated when injected into the germinal vesicle of Xenopus oocytes. We now find that the total amount of stable RNA synthesized by an oocyte with injected nuclei is about twice that of an uninjected oocyte (approximately 15 ng/day). At least half of the RNA transcribed by the injected nuclei is low-molecular-weight RNA of discrete sizes, and is transcribed by RNA polymerase III. Part of this is attributable to a new class of gene (referred to as OAX) which makes a transcript about 180 nucleotides long, and which is activated by at least 50-fold in somatic nuclei injected into oocytes. OAX RNA is not a degradation or processing variant of ribosomal or 5 S RNA, and is not coded by mitochondrial DNA. It enters oocyte cytoplasm, but turns over with a half-life of less than 3 hr, as judged by the culture of enucleate oocyte cytoplasms for several days during which 4 and 5 S RNAs are stable. OAX RNA synthesis is not detected by labelling cultured cells or their nuclei. The results emphasize the selectivity with which components of an oocyte germinal vesicle activate genes in injected somatic nuclei.
先前的研究表明，将培养细胞或红细胞的细胞核注入非洲爪蟾卵母细胞的生发泡后，它们会被转录激活。我们现在发现，注入细胞核的卵母细胞合成的稳定RNA总量约为未注入细胞核的卵母细胞的两倍（约15纳克/天）。注入细胞核转录的RNA中至少一半是大小离散的低分子量RNA，由RNA聚合酶III转录。其中一部分归因于一类新的基因（称为OAX），它产生一种约180个核苷酸长的转录本，在注入卵母细胞的体细胞核中被激活至少50倍。OAX RNA不是核糖体RNA或5S RNA的降解或加工变体，也不是由线粒体DNA编码的。它进入卵母细胞细胞质，但周转半衰期不到3小时，这是通过对去核卵母细胞细胞质进行几天培养判断得出的，在此期间4S和5S RNA是稳定的。通过标记培养细胞或其细胞核未检测到OAX RNA的合成。这些结果强调了卵母细胞生发泡成分激活注入体细胞核中基因的选择性。
