FIG. 7.

Detection of P. aeruginosa exoproduct gene expression by RT-PCR. Table 2 describes the oligonucleotides used for RT-PCR and the predicted size of each amplicon. (A) RT-PCR of mRNA extracted from axenic culture under T3SS-inducing conditions after 6 h of growth. (B) RT-PCR of mRNAs extracted from P. aeruginosa strains cocultured with the human monocytic cell line THP-1 at an MOI of 0.1. (C) RT-PCR of mRNAs extracted from P. aeruginosa strains cocultured with the human monocytic cell line THP-1 at an MOI of 1.0. In accordance with their secreted protein profiles, transcripts for proteases and T3SS exoproducts were not detected by RT-PCR in the ΔnarGH and ΔnirS mutants under any of the conditions tested. toxA transcripts were detected in wild-type PA14 and the ΔnarGH and ΔnirS mutants under T3SS-inducing culture conditions (A) and during the P. aeruginosa interaction with THP-1 cells at an MOI of 1.0 (C) but not at an MOI of 0.1 (B). The toxA expression profiles of the ΔnarGH and ΔnirS mutants correlate with the cytotoxicity data shown in Fig. 3B. −RT, control without reverse transcriptase.