FIG. 5.

(A) Southern blot analysis of partial digestion of AccI-SacI-digested B. aphidicola (P. spyrothecae) DNA by using serial dilutions of XbaI. Lanes: 1 to 8, digestions with 5.0, 2.5, 1.24, 0.63, 0.31, 0.16, 0.08, and 0.04 U of XbaI, respectively, for 15 min. X, A, S, control digestions performed to completion (X, XbaI; S, SacI; A, AccI. Arrows indicate the two principal forms of the plasmid. (B) Proposed structure of pBPs2 from B. aphidicola (P. spyrothecae) containing five tandem repeats of a 1.8-kb unit. Boxes with a similar pattern represent identical genes. All genes are transcribed in a clockwise direction. The region denoted ori? contains the putative origin of replication. Arcs correspond to restriction fragments removed from molecules with AccI and SacI before partial digestion experiment with XbaI. The restriction enzyme sites shown are as in Fig. 4A.