Fig. 4. Gene expression profiles in the dmtA^– mutant. (A) Developmental time course of gene expression. The ecmA and ecmB (prestalk), cotB (prespore) and cprD (growth/differentiation transition) markers are expressed with comparable levels and timing in dimA^– and wild-type cells, from 0-24 hours. The 5 kb dimA transcript is also developmentally regulated in wild-type cells but is absent in the mutant. However, a larger transcript (>7 kb), due to a readthrough transcription into the blasticidin resistance cassette, is detectable. Methylene Blue staining of ribosomal RNA (rRNA) is shown as a loading control. (B) dimA transcripts are expressed in both prespore and prestalk cells at the slug stage of development, although the highest levels are detectable in prespore cells. The purity of the isolated cell populations is indicated by the great enrichment of ecmA and ecmB in prestalk cells, and cotB in prespore cells.