are slugs more successful than amoebae at traversing soil to locate bacterial food?
We examined whether D. discoideum slugs were more successful than amoebae at crossing soil to find bacteria. We prepared soil plates by placing a 0.5-cm thick, 6-cm wide layer of autoclaved topsoil on top of a water agar plate, leaving 1.5-cm strips of exposed agar on opposite sides of the plate. On one side, we applied a 1-cm wide by 6.5-cm long strip of bacterial slurry to the agar, and on the other agar side we delivered 1 x 107 D. discoideum cells to the plate (Figure 1c). The D. discoideum wild-type strain AX4 and aggregation mutant CAP2 were raised axenically, without bacteria, in HL5 liquid medium. We centrifuged each strain twice for 3 min at 1000 r.p.m., diluted them with KK2 buffer to 1 x 107 cells/ml, and delivered 1 ml of each strain’s cell solution to 10 plates. We obtained the adenylyl cyclase null aggregation mutant CAP2 from the Dictyostelium Stock Center where Carole Parent had deposited it (www.dictybase.org). Adenylyl cyclase null mutants fail to produce the cyclic a
