Hartley M R, Ellis R J
Biochem J. 1973 May;134(1):249-62. doi: 10.1042/bj1340249.
Chloroplasts isolated from young spinach leaves incorporate [(3)H]uridine into RNA. This incorporation shows an absolute requirement for light and does not occur in lysed chloroplasts. Fractionation by polyacrylamide-gel electrophoresis of the RNA synthesized in vitro reveals a major discrete product of molecular weight 2.7x10(6) and two minor products of molecular weight 1.2x10(6) and 0.47x10(6). These discrete products are super-imposed on a background of polydisperse RNA. The incorporation of (32)P(i) into chloroplast rRNA species (mol.wt. 1.05x10(6) and 0.56x10(6)) in excised spinach leaves proceeds after a distinct lag period compared with the incorporation into cytoplasmic rRNA species (mol.wt. 1.34x10(6) and 0.7x10(6)). Incorporation of (32)P(i) into chloroplast RNA species of molecular weight 2.7x10(6), 1.2x10(6), 0.65x10(6) and 0.47x10(6) proceeds without such a time-lag. The kinetics of labelling of the individual RNA components is consistent with the rapidly labelled RNA species of molecular weight 1.2x10(6) and 0.65x10(6) being precursors to the more slowly labelled rRNA species of molecular weight 1.05x10(6) and 0.56x10(6) respectively.
从幼嫩菠菜叶中分离出的叶绿体可将[³H]尿苷掺入RNA中。这种掺入绝对需要光照，在裂解的叶绿体中则不会发生。对体外合成的RNA进行聚丙烯酰胺凝胶电泳分级分离，结果显示有一个主要的离散产物，分子量为2.7×10⁶，还有两个次要产物，分子量分别为1.2×10⁶和0.47×10⁶。这些离散产物叠加在多分散RNA的背景之上。与掺入细胞质rRNA种类（分子量为1.34×10⁶和0.7×10⁶）相比，在离体菠菜叶中³²P(i)掺入叶绿体rRNA种类（分子量为1.05×10⁶和0.56×10⁶）有一个明显的延迟期。³²P(i)掺入分子量为2.7×10⁶、1.2×10⁶、0.65×10⁶和0.47×10⁶的叶绿体RNA种类时没有这样的时间延迟。各个RNA组分的标记动力学与分子量为1.2×10⁶和0.65×10⁶的快速标记RNA种类分别是分子量为1.05×10⁶和0.56×10⁶的较慢标记rRNA种类的前体这一情况相一致。
