Figure 9.

(A) Phototactic behavior of GRP125-deficient slugs (GRP125⁻/17, GRP125⁻/18, and GRP125⁻/C) in comparison with AX2 slugs. Cells (1 × 10⁷) were incubated for 3 d in a phototaxis chamber. Subsequently, trails and cell material were blotted and stained with Coomassie Blue. The light hole and light path in the chamber are represented by the arrow and horizontal line; the outline of the phototaxis chamber is indicated as well. Points of cell application, apparent from the mass of spore material formed, are aligned, illustrated by the vertical line in light gray. AX2 slugs directly approach the light hole along the light path; slugs of mutants deviate shortly after the start of migration and progressively lose orientation. (B) Migration in complete darkness of GRP125-deficient slugs in comparison with AX2 slugs. Cells (1 × 10⁷) were incubated for 3 d in complete darkness in the phototaxis chamber and processed as in A. The capacity for long-range migration is not altered by GRP125 deficiency. (C) Photodetection of GRP125-deficient and AX2 fruiting bodies. A lawn of E. coli B/2 was point inoculated, incubated for 4 d in the phototaxis chamber, and photographed. Consecutive frames in the top row (1–3) show experiments using AX2, and those in the lower row (4–6) show GRP125⁻. Arrows indicate the position of the light hole. Bar, 1 cm. Fruiting bodies turned to the direction of the light source in the presence and absence of GRP125.