Figure 3.

Developmental kinetics of RIP3 gene expression and the requirement of RIP3 for expression of aggregation and postaggregative genes. (A) RNA blot analysis of the expression pattern of RIP3 using RNA isolated at different stages of Dictyostelium development. Mound formation occurs at ∼8 h and culmination initiates at ∼18–20 h. (B) Expression of aggregation-stage, postaggregative, and cell-type-specific genes in wild-type and rip3 null cells in suspension culture in response to cAMP. Cells were pulsed for 5 h with 30 nM cAMP (5p). Cells were given cAMP under slow-shake suspension conditions, which allow cell-cell interactions (120 rpm), to 300 μM and were supplemented to 300 μM every 2 h. 8+ and 11+ represent time points (hours) after the initiation of the experiment. The plus sign represents the addition of exogenous cAMP. Minus cultures (8− and 11−) did not receive exogenous cAMP. Cultures were split after 5 h of cAMP pulsing. csA (Contact Sites A) is a marker for aggregation-stage gene expression; CP2 is a marker for postaggregative gene expression. SP60/CotC is a prespore-specific gene; ecmA is a prestalk-specific gene.