FIG. 1.
High-pressure frozen/freeze-substituted E. coli during RP4-mediated conjugation on solid substrate (filter mating). The donor contained RP4-Tra1 and RP4-Tra2 [E. coli HB101(pML123, pVWDG23110Δ0.2)], and the recipient was E. coli SCS1 (Rifr). (A) Lower magnification of mating cell aggregates. Arrows indicate junctions; s indicates the forming septum. Bar, 0.5 μm. (B) Junctions between pairs of bacteria (arrows). Bar, 0.25 μm. (C) High magnification of junction showing electron-dense area between outer membranes (arrow), lightly staining outer membrane (OM), dense periplasmic gel (P), and lightly staining inner cytoplasmic membrane (CM). Bar, 100 nm.