Berthold W, Lim L
Biochem J. 1976 Feb 15;154(2):517-27. doi: 10.1042/bj1540517.
High-molecular-weight RNA was isolated from rat brain at various times after the intracranial administration of [32P]Pi. The synthesis of 28S and 18S rRNA could be detected within 1h of the injection of the radioactive precursor and appeared to be more pronounced, relative to other high-molecular-weight RNA, in the brains of older rats compared with those of newborn rats. Polyadenylated RNA, representing most mRNA and their precursors, was isolated by chromatography on oligo(dT)-cellulose. The contribution of this polyadenylated RNA to total RNA synthesis was investigated in the cerebral cortex and the phylogenetically older brain stem at different stages in the development of the rats by using a 5h period of labelling as an arbitrary index of transcription. In the brain stem the proportion of labelled polyadenylated RNA comprised 27-30% of the total RNA. The corresponding values for the cortex decreased from 34% in newborn rats to 23% in 40-150-day-old rats. These data indicated that proportionately more polyadenylated RNA is synthesized in the cortex of the newborn than in the adult rat and that there is a progressive decrease in the synthesis of polyadenylated RNA relative to rRNA during development.
在向大鼠颅内注射[32P]Pi后的不同时间，从大鼠脑部分离出高分子量RNA。在注射放射性前体1小时内即可检测到28S和18S rRNA的合成，与新生大鼠相比，老年大鼠脑中的这种合成相对于其他高分子量RNA似乎更为明显。通过寡聚（dT）-纤维素柱层析分离出代表大多数mRNA及其前体的聚腺苷酸化RNA。通过使用5小时的标记期作为转录的任意指标，研究了这种聚腺苷酸化RNA对大鼠发育不同阶段大脑皮层和进化上较古老的脑干中总RNA合成的贡献。在脑干中，标记的聚腺苷酸化RNA占总RNA的比例为27%-30%。皮层的相应值从新生大鼠的34%下降到40-150日龄大鼠的23%。这些数据表明，新生大鼠皮层中聚腺苷酸化RNA的合成比例高于成年大鼠，并且在发育过程中，相对于rRNA，聚腺苷酸化RNA的合成逐渐减少。
