mRNA expression from msp genes during sporulation. RT-PCR was used to determine the relative levels of expression of 16S rRNA (A), mspA (B), mspB (C and E), and mspC (D) genes during myxospore development. Lanes 1 contained negative control PCR mixtures in which different primer sets were used to amplify products from RNA preparations that had been treated with DNase but not reverse transcribed. Lanes 2 contained positive control PCR mixtures in which chromosomal DNA was used as the PCR template. Lanes 3 contained DNA ladders. One microliter of each DNase-treated, reverse-transcribed reaction mixture was used as a template for PCRs (lanes 4 to 9). (A to D) Lane 4, zero time (just before aliquots of vegetative cells were spotted onto TPM starvation plates); lane 5, starvation for 24 h; lane 6, starvation for 48 h; lane 7, starvation for 72 h. (E) Lane 4, zero time; lane 5, starvation for 6 h; lane 6, starvation for 12 h; lane 7, starvation for 18 h; lane 8, starvation for 24 h; lane 9, starvation for 30 h.