Fig. 3. MEGAP mutant phototaxis and development. (A) Terminal fruiting bodies of cell lines developed on nitrocellulose membranes for 48 hours. Scale bar: 2 mm. (B) Aggregation territories of cell lines on nutrient-free agar. A large quantity of nonstreaming cells can be observed in mgp1 mutants. mgp2 mutants often have larger aggregation centres than the wild type. Scale bar: 500 µm. (C) Phototaxis of slugs to a point light source. Light-directed migration of slugs after 48 hours on 0.5% charcoal agar shows that mgp^– slugs are defective in phototaxis. Asterisks indicate the direction of the light source. Scale bar: 2 mm. (D) Representative examples of wild-type and mgp mutant slugs when cells are developed on nutrient-free agar. mgp1^– slugs are shorter than the wild type and large clumps of cells remain on the substratum. mgp2^– mutants form a few very large slugs and numerous shorter slugs. mgp1^–/2^– slugs are also longer than wild-type slugs. Scale bar: 250 µm. Images are representative of three experiments.