Wild-type PPR1 mRNA also accumulates in upf2Δ, upf3Δ, dcp1Δ and xrn1Δ cells. (A) PPR1 mRNA accumulation in HFY1200 (wild-type), HFY870 (upf1Δ), HFY1300 (upf2Δ) and HFY861 (upf3Δ) yeast cells grown in YAPD. (B) PPR1 mRNA accumulation in yeast cells HFY1200 (wild-type), HFY1067 (dcp1Δ) and HFY1081 (xrn1Δ) grown in YAPD. The northern blots were prepared using 15 µg of total RNA and hybridized with radiolabeled PPR1, CYH2 and ScR1 DNA. The relative PPR1 steady-state levels are indicated under the northern blots hybridized with radiolabeled PPR1 DNA.