(A) Top, SNR13-TRS31 genomic locus and transcription products. The transcriptional readthrough product is indicated as SNR13-TRS31. (A–D) Northern analysis using a TRS31 probe and RNA isolated from the following yeast strains: (A) wt (KY661), rtf1Δ (KY656), paf1Δ (KY685), ctr9Δ (GHY1094), cdc73Δ (KY689), leo1Δ (GHY250), and ctk1Δ (KY586); (B) wt (FY118), spt4Δ (GHY166), spt5-194 (KY718), spt5-242 (FY1635), fcp1-110 (PCY448), and ctk1Δ (KY586); (C) SPT16 (FY118) and spt16-197 (FY348); and (D) wt (FY118), set1Δ (KY910), set2Δ (KY912), and dot1Δ (KY903). For each strain in (C), one-half of a log phase culture was shifted to 39°C for 80 min to inactivate the spt16-197 gene product (Kaplan et al., 2003). The remaining culture was kept at 30°C for 80 min.