FIG. 3.

Exosome mutants have defects in processing of polycistronic snoRNAs. Shown are two different exposures of the same Northern blots containing RNA from the indicated strains. All strains were grown in YEP–2% galactose to early to mid-log phase. The ski2Δ, ski3Δ, ski8Δ, and rrp6Δ strains were grown at 30°C. The ski6-100, rrp4-1, mtr3-1, and mtr4-1 strains were grown at 24°C and incubated for an additional hour at 37°C. Blots were probed for snR190 (A), U14 (B), snR73 (C), snR72 (D), 3′-extended U14 (E), 3′-extended snR73 (F), or 3′-extended snR72 (G). The species of 385 nt seen in panels A and B likely represents a dicistronic precursor, while the species of 184 nt seen in panel B likely represents U14 that contains a 5′ extension but carries the mature 3′ end. Based on known Rnt1p cleavage sites, the 238-nt species seen in panels C and F likely represents snR73 that has been released from its precursor but carries 5′ and 3′ extensions. wt, wild type. Positions of size markers (lanes M) are given in nucleotides.