Fig. 4. gtaC^- null cells exhibit DIF responses that are absent from dimA^- mutant cells. (A) Alignment of the GATA DNA-binding domain of GtaC with the DNA-binding domain of mouse GATA1, Drosophila Pannier and Neurospera WC-2. (B) Schematic of the gtaC gene and gene disruption. The region encoding the GATA DNA-binding domain is shaded black, poly asparagine repeats are blue and poly glutamines are green. Approximately three-quarters of the gtaC-coding sequence was replaced with a blasticidin cassette, including the predicted GATA DNA-binding domain. (C) Measurement of DIF responsive gene expression in monolayer assays. Expression of prestalk markers (ecmA and ecmB) and prespore markers (psA and cotB) was measured by qPCR. Cells were treated with cAMP for 9 hours before addition of DIF for 1 (ecmA and ecmB) or 3 hours (psA and cotB). gtaC^- cells exhibit responses comparable with those of wild-type cells, whereas no responses were seen in dimA^- cells. Results shown are from one experiment. Comparable results were seen in at least three independent experiments. (D) DIF responsive gene expression in dissociated cell assays. Mound stage cells were dissociated before shaking in cAMP with or without DIF for 2 hours. Expression of prestalk markers (ecmA and ecmB) and prespore markers (psA and cotB) was measured by qPCR. gtaC^- cells exhibit comparable responses with those of wild-type cells, whereas no responses were seen in dimA^- cells. Results shown are from one representative experiment. Comparable results were seen in at least three independent experiments.