Fig. 3

Intron size distribution. The graphs show the number of introns as a function of their size for Paramecium tetraurelia, biaurelia, sexaurelia and caudatum. For each species, 3 curves are superimposed: introns predicted by TrUC (gray), introns in the v1 annotations (red) and introns in the v2 annotations (blue). The v2 introns are the subset of TrUC introns in gene models and additional introns predicted by Eugene without RNA-Seq support. The P. tetraurelia v1 introns were intentionally filtered when greater than 45 nt [6]. In all cases, the great majority of introns are smaller than 40 nt. In v1 annotations (except P. tetraurelia), there are more large introns than in TrUC or v2 annotations. Since the RNA-Seq (TrUC predictions) are expected to show the true distribution of intron sizes, we are more confident in the v2 annotations