FIG. 3.

Extracellular signal exchange leading to aerial growth in S. coelicolor. The figure, based on data of Willey et al. (121) and Molle and Buttner (78), is modified from the work of Chater (16) with permission. The lower part depicts how substrate hyphae in different physiological states under bld gene control may produce signals that act in a cascade leading to production of SapB, which is thought to allow formation of aerial hyphae (one is illustrated near the top of the figure).