Features predisposing transcripts to NMD. Indicated are the percentage of genes exhibiting the measured feature (y-axis), the number of stages at which this is observed (x-axis) and the fold increase in gene intensity in smg-1(r861) over N2 (z-axis, log2 scale). In each case the average background occurrence of the feature is indicated by the grey square. The measured features are: (a) percentage of genes with a uORF; (b) percentage of genes with expressed introns; (c) average 3' UTR length; (d) the total percentage occurrence of the above three NMD features for the set of over-expressed genes. The plots show a clear positive correlation between the feature examined and the increased effect of NMD on the transcripts.