Such a critical time threshold in 3rd day is apparent also in connection with the effect of added MRT67307 supplier glucose (see below, Figure 3d). Effect of media The standard appearance of IWP-2 supplier the F phenotype (Figure 2b) was described for colonies grown on nutrient agar NA supplemented with 27 mM glucose (NAG). Replacement of glucose by sorbitol or mannitol at the same concentration allows for a “partial” F pattern. Lower glucose concentrations (0.27 or 2.7 mM) do not support standard patterning; higher concentration (54 mM) deforms the final pattern. Semi-defined medium of comparable composition (TN, or TN with added glucose) supports healthy growth

of well-formed colonies, albeit with a patterning different from the phenotype grown on NAG. Finally, polyethylene glycol (PEG) added to NA in amount mimicking the osmotic load caused by 27 mM glucose did not promote the standard development (Figure 3c). Effect of glucose addition during development At various times after planting on NA, F colonies were “circumscribed” with glucose solution, to achieve its concentration, in the agar, in the range of about 27 mM in the immediate vicinity of the colony. As shown in Figure 3d, the older the colony, the more difficult for it to accomplish the standard appearance Go6983 after glucose addition: after the 3rd day the “struggle towards form” became distorted, and the inner (intermediate) ring did

not appear at all (even if under normal condition it grows until 5th day; see [3]). All these effects of culture conditions are fully reversible in the sense that cell material taken from “atypical” colonies reverts to standard appearance when planted to NAG;

thus, we are dealing with true developmental plasticity rather than selection of variants. Morphotype F: development in the presence of neighbors As already reported, F colonies are very sensitive towards Baf-A1 neighboring bodies on the dish. Closely planted F (or Fw, or F and Fw) colonies grow into a confluent colony with multiple centers and a common rim. An F macula will inhibit normal growth and patterning of F (or Fw) colonies growing in their vicinity, even when planted across a mechanical septum. Finally, heterospecific bodies (colonies or maculae of S. rubidaea or E. coli) were shown to induce formation of a new quality, a special pattern named X structure, characterized by an additional ring round the standard F colony [3, 20]. Here we investigated the formation of X bodies in a closer detail (Figure 4; see also Figure 5a). First, we found that even the M clone (i.e. the rimless derivative of F) can induce the X structure in F. We also found that, in contrast to standard development, there is no critical period of induction: the X structure will appear also on an older, or even adult and non-growing F colony, if a non-F body is planted nearby.