Bird R C, Zimmerman A M
Cell Tissue Kinet. 1984 Sep;17(5):535-44. doi: 10.1111/j.1365-2184.1984.tb00612.x.
The protozoan, Tetrahymena pyriformis GL, was used as a model system for studying polysomal mRNA during the cell cycle and during cilia regeneration. Our previous work has shown a substantial induction of tubulin synthesis following deciliation and during G2 of the synchronous cell cycle. In the present study, the abundance of tubulin mRNA on polysomes was examined in order to determine whether more tubulin mRNA was being translated during the periods of peak tubulin synthesis. Polysomes isolated at sequential times following deciliation and during the synchronous cell cycle were translated in a cell-free translation system derived from wheat germ. The abundance of tubulin mRNA on polysomes was inferred from the amount of tubulin translated in vitro. Following deciliation and prior to the peak period of tubulin synthesis, the abundance of tubulin mRNA (at 140 min post-deciliation) increases to 25 times the initial value observed (at 20 min post-deciliation). Since the increase in tubulin mRNA abundance precedes the peak in tubulin synthesis, induction of tubulin synthesis appears to be mRNA-dependent. A similar analysis of tubulin mRNA abundance on polysomes during the synchronous cell cycle revealed a peak of tubulin mRNA prior to each peak of tubulin synthesis. These studies suggest that the periodic fluctuations in the synthesis of tubulin are dependent upon fluctuating levels of tubulin mRNA on polysomes.
原生动物梨形四膜虫GL被用作研究细胞周期和纤毛再生过程中多聚核糖体mRNA的模型系统。我们之前的工作表明，在去纤毛后以及同步细胞周期的G2期，微管蛋白合成有显著诱导。在本研究中，检测了多聚核糖体上微管蛋白mRNA的丰度，以确定在微管蛋白合成高峰期是否有更多的微管蛋白mRNA被翻译。在去纤毛后和同步细胞周期的连续时间分离的多聚核糖体在源自小麦胚的无细胞翻译系统中进行翻译。多聚核糖体上微管蛋白mRNA的丰度是根据体外翻译的微管蛋白量推断出来的。去纤毛后且在微管蛋白合成高峰期之前，微管蛋白mRNA的丰度（去纤毛后140分钟）增加到观察到的初始值（去纤毛后20分钟）的25倍。由于微管蛋白mRNA丰度的增加先于微管蛋白合成的高峰期，微管蛋白合成的诱导似乎是mRNA依赖性的。对同步细胞周期中多聚核糖体上微管蛋白mRNA丰度的类似分析显示，在每个微管蛋白合成高峰期之前都有一个微管蛋白mRNA的峰值。这些研究表明，微管蛋白合成的周期性波动取决于多聚核糖体上微管蛋白mRNA水平的波动。
