Below: colony pattern distribution at day 7; filled dots – standard F colonies; open dots – imperfect F pattern (see inset; bar = 5 mm); grey zone: interval of colony diameter in PU-H71 in vitro controls (no macula). Note the critical distance of ca 18 mm indicating the breakdown of typical F structure. b. Effect of maculae of different origin (as indicated) on the development of F colonies. Left column: synchronous planting, common space. Middle and right: macula

separated from colonies by a septum (arrow), but sharing the gas phase. Middle: synchronous planting. Right: colonies planted to 3d macula. Insets: controls without maculae. Day 5 after colony inoculation, bar = 1 selleck compound cm. In settings without a septum containing R or E. coli macula, note development of X phenotype. The R macula, as well as a macula of E. coli, induced, again, formation of the X phenotype in colonies of the F clone (Figure 4b, left;

compare to Figure 2). No such X-like structures were observed when R colonies were planted in the vicinity of an E. coli macula (not shown). Communication across obstacles If the macula and colonies have been grown on opposite see more sides of a septum dividing the dish, preventing diffusion in the semi-solid agar matrix but allowing gas exchange, the effect of macula was qualitatively similar to that on a shared plate, albeit the distance between the bodies appeared as if increased for simultaneously planted bodies (Figure 4b, middle). If, however, the macula across the septum was at least 3 days old at the time of colony inoculation, colony development was similar to controls sharing a continuous plate (Figure 4a, insert), suggesting that older bacterial bodies produce volatiles that may be absorbed by the agar medium. Maculae of a different strain (R) or species (E. coli) also affected development of F colonies across an obstacle; however, they never induced formation of the X structure across the septum, indicating that

Miconazole signals diffusing through the semi-solid substrate, distinct from those carried by the gas phase, are indispensable for the development of the X pattern. The effect across the septum is not bound to an organized body of the macula: bacterial suspension (F) kept across the septum exerted an effect comparable to that of a macula (Figure 5a; compare to Figure 4b). Figure 5 Manipulating F colonies via the gas phase. a. Cross-septum effects. Colonies are shown 4 days after planting into a compartment of a septum-divided Petri dish containing in its other compartment (i) bacterial (F) suspension; (ii) F-macula previously grown for 3days on a cellulose membrane; (iii) macula-conditioned agar obtained by growing a macula as in (ii), but removing it (with the membrane) immediately before colony planting; (iv) macula-conditioned agar obtained as in (iii), but colonies planted on a virgin agar (i.e. the agar medium in the colony compartment has been exchanged prior to colony plating).