Figure 5.

Identification of Ll.LtrB 3′ ends in vivo. Free intron 3′ ends were amplified by RT-PCR from L. lactis total RNA extracts. (A) Intron 3′ ends were identified by first extending the intron RNA with a polyA tail followed by the synthesis of a cDNA with an oligo dT. The RNA strand was removed by an RNAse H treatment and the single strand DNA amplified by PCR. (B) The PCR reactions were ran on a 2% agarose gel and the chromatogram of some of the sequenced bands are shown (C–D). The same procedure was repeated for the Ll.LtrB-ΔA construct but extending a polyU instead of a polyA tail at the 3′ end of the intron (E).