Fig. 9. A schematic representation of the regulatory roles fulfilled by Dd-STATc. This is a representation of the promoters of the two classes of gene known to be regulated by Dd-STATc. The promoter of the ecmA gene is under the negative control of Dd-STATc; the element(s) that normally direct ecmA expression only in pstA cells are repressed by Dd-STATc; such that in a Dd-STATC null strain they become ectopically active in the pstO cells (Fukuzawa et al., 2001). Activation of Dd-STATc in pstO cells is under the direct control of DIF. As we have shown, gapA and rtoA are regulated at two levels. They display semiconstitutive activity during growth and development and they are super-inducible, above this level, by hyperosmotic stress. We assume that different promoter elements are utilised for these different activities. We also know that gapA and rtoA are not induced by DIF, that is, the DIF and the stress signalling pathways do not display 'cross talk', and two possible explanations for this are presented in the text.