Fig. 9. Analysis of expression directed by the complete ecmA promoter in control cells, mybE– cells and mybE– cells expressing a MybE:GFP fusion gene. (A) The ecmAO-lacZ construct and the pspA gus constructs were co-transformed into Ax2 cells and mybE– cells, and their spatial expression patterns were determined, by double staining at the slug stage. (B) Cells transformed as in A were analysed at the slug stage for lacZ expression alone, i.e. for the activity of the ecmAO promoter fragment. (C) MybE– cells were co-transformed with a MybE:GFP fusion construct under the transcriptional control of a semi-consitutive promoter and with ecmAO-lacZ. The panels on the right show a phase-contrast image of growing cells juxtaposed with the GFP fluorescence image of the same field. The panel on the left shows slugs, derived from the same population, and stained for lacZ expression.