Figure 6.

Pulse–chase analysis of pre-rRNA processing. Strains bearing nop2 ts alleles and YBH31 (NOP2) were grown at 25°C and shifted to 37°C for 2 h. YBH23 (nop2-10) was shifted instead to medium containing 3% formamide (+ FA) and grown for 2 h at 25°C. A 2 min labeling pulse with [³H-methyl]-methionine was followed by chase times of 2, 4, 8 or 12 min. Labeled RNAs were separated on 1% glyoxal-agarose gels and visualized by fluorography. Precursor and mature rRNAs are indicated on the left. The 23S intermediate is indicated with an asterisk.