Figure 4.

A cluster that exhibits a non-canonical intron. The two dark blue lines at the top represent predicted transcripts, the red line below them represents the genome, and the six following purple lines represent ESTs. The gap indicated by the black arrow begins with AA and ends with TT (i.e., it is a non-canonical intron). The gap is 54 bases long, which is similar to many of the observed non-canonical introns found in problematic libraries. The gap occurred only in the sequence that came from a library detected as possibly contaminated; it may correspond to sequence that was incorrectly deleted from some ESTs. This gap resulted in the prediction of a splice variant (transcript_1) that is likely spurious.