Transcriptional organization of the pilF locus. To examine the transcriptional organization, RNA was isolated and subjected to RT-PCR analyses. (A) The primers and expected fragments are indicated and labeled 1 to 4. RNA was used as a negative control; chromosomal DNA was used as a positive control. (B) The resulting DNA fragments were separated on a 0.8% agarose gel. Lanes 1, chromosomal DNA from T. thermophilus; lanes 2, cDNA from T. thermophilus HB27; lanes 3, cDNA from T. thermophilus pilF::kat; lanes 4, RNA control.