Fig. 6. Cell-type specific gene expression in tagA mutants. (A) Cells expressing a lacZ reporter gene under the control of the tagA promoter in a wild-type or tagA mutant background were plated as pure populations and stained with X-gal. The arrows indicate the stained regions in the mutant. Scale bars: 0.1 mm. (B) RNase protection analysis of tagA mRNA in purified spores and stalks reveals a reproducible enrichment of tagA mRNA in the stalk RNA of the tagA mutant. Controls are 2- and 4-hour developing wild-type cells and 10% of the input probe, not treated with RNase. (C) A cotB/lacZ reporter was used to visualize prespore/spore gene expression. An unstained wild-type stalk (left panel) is in stark contrast to the stained stalk cells of the tagA mutant (3 right panels). A portion of the cotB-positive sorus is shown above the tagA mutant stalk (middle). D. Northern analyses of spore and stalk RNAs with probes for the spiA (spore-specific) and ecmB (prestalk/stalk-specific) genes.