Examination of the polar effects due to the melF insertion mutation. RT-PCR studies to evaluate the effects of the Mu insertion on mel2 transcription upstream (melFu) and downstream of the insertion site (melFd, melH, melI, melJ, melK). Equivalent amounts of RNA from M. marinum wild type and the M. marinum melF mutant were reverse transcribed and subjected to PCR with specific oligonucleotides within each gene. Equal amounts of each PCR product were loaded on 0.8% agarose gels and compared to the 16S rRNA control RT-PCR reaction for each strain (16S rRNA) carried out on the same samples. Data shown are representative of two independent experiments.