Ju Q, Warner J R
Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461.
Yeast. 1994 Feb;10(2):151-7. doi: 10.1002/yea.320100203.
We have measured the content of ribosomes, the rate of synthesis of ribosomal RNA, and the level of the mRNA for ribosomal proteins as a culture of Saccharomyces cerevisiae passes through the growth cycle. The transcription of both ribosomal RNA and ribosomal protein genes disappears at an unexpectedly early stage in the growth cycle, accompanied by a decline in the total RNA content of the culture by nearly 50% and a decline in the number of ribosomes per cell to less than 25% of the maximum value. During this time the cells continue to grow through more than two doublings, initially at the normal log growth rate, which then decline gradually for several hours. The data suggest that the cell can sense an unfavorable change within the medium and responds by employing regulation of both synthesis and degradation of its ribosomes. We conclude that the cell regulates ribosome synthesis and content according to its estimate of the potential for growth.
我们测定了酿酒酵母培养物在生长周期中核糖体的含量、核糖体RNA的合成速率以及核糖体蛋白mRNA的水平。核糖体RNA和核糖体蛋白基因的转录在生长周期中一个出乎意料的早期阶段消失，同时培养物的总RNA含量下降近50%，每个细胞的核糖体数量降至最大值的不到25%。在此期间，细胞继续生长超过两个倍增周期，最初以正常的对数生长速率生长，随后在数小时内逐渐下降。数据表明，细胞能够感知培养基内的不利变化，并通过对核糖体的合成和降解进行调控来做出反应。我们得出结论，细胞根据其对生长潜力的估计来调节核糖体的合成和含量。
