Figure 4.

Abnormal initiation of development in phg2 mutant cells is cell-autonomous. (A) Wild-type cells expressing the green fluorescent protein (WT-GFP) were mixed with phg2 mutants, cocultured for 48 h, and then incubated in a medium containing 9% HL5. At the onset of multicellular development, fluorescent wild-type cells did not enter multicellular aggregates (indicated by arrows). Examination of the cells at high magnification in the same experiment (lower panel) revealed that wild-type cells retained a mostly spherical shape typical of unstarved cells. (B) Phg2-GFP cells were mixed with wild-type cells and treated as described in A. Phg2 mutant cells accumulated in cellular aggregates and adopted the elongated shape typical of developing cells (lower panel). Bar, 50 μm.