Fig. 11. Analysis of DIF induction of ecmA in a control and a mybE– mutant. (A) Expression of promoter constructs. The mybE– strain and a control random integrant strain, both transformed with the indicated ecmA promoter fusion constructs, were assayed for DIF inducibility in the monolayer assay. Quadruplicate wells were analysed for each assay condition and this result is typical of four separate biological experiments. (B) RT-PCR analysis of the ecmAO:lacZ gene and the endogenous ecmA gene. Control and mybE– cells, transformed with ecmAO:lacZ, were induced with DIF-1 in a monolayer assay using a cell density of 10⁵/cm² and a cerulenin concentration of 50 µM. Total cellular RNA was extracted and the abundance of the lacZ, ecmA and Ig7 RNAs (a constitutively expressed gene, used as a loading control) in the two strains was determined by semi-quantitative RT-PCR.