Figure 4.

Mutant U3 snoRNAs are stable 2 h after injection. ³²P-labeled U3 snoRNA (mutants or wild type) were injected into oocyte nuclei, and the isolated RNA was analyzed by gel electrophoresis 2 h after injection. ³²P-labeled U2 snRNA was coinjected as an internal control to normalize for any differences in injection or recovery of the samples. The stability results are from different experiments for the various mutants, and the amounts of coinjected U3 vs. U2 varied between experiments. For any given mutation, the ratio of U3 to U2 between 0 and 2 h shows that all the mutants are stable at the 2-h time point used for analysis of nucleolar localization, except for the Box C′ mutant, which has partially degraded relative to the U2 snRNA internal control.