Fig. 4. Analysis of point mutations within the 22-mer region determined within the context of a 94-mer construct. (A) Expression patterns for the mutant 94-mer constructs. The control construct contains the minimal, 94 nucleotide ecmO promoter region, upstream of basal promoter elements in a lacZ reporter construct. Three analogous constructs were made, bearing the point mutations indicated by lower case letters and described in the text. The spatial expression patterns of the four constructs were determined at the slug stage. (B) Analysis of DIF-1 inducibility of the mutant 94-mer constructs. The four constructs analysed in A were rendered DIF-competent and either induced or not induced with DIF-1. The lacZ expression level was determined and the ß-galactosidase activity with DIF-1 is shown normalised to the activity without DIF-1.