Measurement of rRNA Synthesis and Degradation Rates by H-Uracil Labeling in Yeast.

In order to measure the actual synthesis and degradation rates (SR, DR) for rRNA in yeast, we developed a method based on the pulse labeling and quantification of newly synthesized large rRNA molecules by a known mass of cells. The SR is calculated as the ratio of new rRNA molecules (synthesized after a short [5,6-H]-uracil pulse) to total rRNA (a proxy of cell mass), calculated by northern blotting after hybridization with a P-labeled rRNA probe. Then to measure the DR we perform a chase of the existing H-labeled rRNA for several hours during yeast culture growth.

Influence of cell volume on the gene transcription rate.

Cells vary in volume throughout their life cycle and in many other circumstances, while their genome remains identical. Hence, the RNA production factory must adapt to changing needs, while maintaining the same production lines. This paradox is resolved by different mechanisms in distinct cells and circumstances.