Figure 4.

Genetic crosses to visualize transfer and intramycelial plasmid spreading of pIJ303 and its derivatives. Dilutions of S. lividans TK54 containing derivatives of plasmid pIJ303 (thio^R) were streaked on a lawn (~10⁶ spores) of plasmid free TK64::pSET152 (apra^R) on R5 plates, as schematically illustrated (A). Pock structures associated with the conjugative plasmid transfer were visible after 2 days of incubation at 30°C (B). After 7 days of incubation the fully sporulated plate (C) was replica plated on LB containing apramycin and thiostrepton to select for transconjugants (D). Pock diameters and sizes of the transconjugant areas indicating efficiency of conjugative transfer and intramycelial plasmid spreading were approximately the same for all derivatives of pIJ303.