Detection of yvfTU expression by RT-PCR. Reverse transcriptase (RT) PCR experiments performed on the yvfTU operon of B. cereus strains ATCC 14579, INRA AF2, NVH 391/98, and NVH 883/00. The operon encodes the YvfTU two-component system. Lanes 1: RT-PCR on 500 ng RNA. Lanes 2: Negative control (RT-PCR on 500 ng RNA with a heat-inactivated reverse-transcriptase). Lanes 3: Positive control (PCR on 200 ng genomic DNA). The ~700 bp PCR product covered the 3'-region of yvfT running into the 5'region of yvfU, indicating that these two genes were expressed in a single operon.