FIG. 1.

Deletion of UPF1, NMD2, or UPF3 stabilizes the can1-100 transcript and promotes nonsense suppression. (A) Deletion mutants that inactivate NMD stabilize the can1-100 transcript. Total RNA isolated from yeast strains with the indicated UPF/NMD genotypes was analyzed by Northern blotting with DNA probes that detected the can1-100 and CYH2 transcripts. WT, wild type. (B) Deletion of UPF1, NMD2, or UPF3 leads to a canavanine-sensitive phenotype. Aliquots (10 μl) of each of four 1:10 dilutions of liquid cultures of each yeast strain were spotted on SC-arg plates containing either 0 or 100 μg of canavanine per ml (− Canavanine or + Canavanine, respectively) and grown at 30°C for 2 days. (C) Deletion of DCP1 or XRN1 does not suppress the can1-100 mutation. Aliquots of serial 1:10 dilutions of each yeast strain were spotted on plates without or with canavanine as in panel B. Because these two mutants had slow doubling times, growth comparable to that of wild-type cells was obtained by maintaining the xm1Δ strain at 30°C for 3 days and the dcp1Δ strain at 30°C for 4 days.