FIG. 3.

Substrates of the 5′→3′ mRNA decay pathway have longer half-lives in the tpa1Δ strain. (A) The effect of the tpa1Δ mutation on the NMD pathway was evaluated by monitoring the CYH2 pre-RNA by Northern blot analysis in WT, tpa1Δ, and upf1Δ strains. A representative blot is shown. (B) Quantitation of the amount of mature CYH2 mRNA remaining at specific times after transcription inhibition by thiolutin was monitored by Northern blot analysis. (C) Quantitation of the amount of mature ACT1 mRNA remaining at specific time points after transcription inhibition by thiolutin was monitored by Northern blot analysis. The abundance of each indicated mRNA was normalized to the level of 25S rRNA in each gel lane. The half-lives (in minutes) for the CYH2 and ACT1 mRNAs are indicated for the WT and tpa1Δ strains. Each time point shown is the mean ± standard deviation from three separate experiments.