Chapter 22 Methods for Manipulating and Investigating Developmental Timing in Dictyostelium discoideum

This chapter describes methods for obtaining reproducible developmental timing, dissecting and characterizing the program of temporal regulation, obtaining timer mutants, initiating rapid recapitulation, initiating erasure and the subsequent program of dedifferentiation, and stimulating simultaneous programs of dedifferentiation and redifferentiation in the same cells. The chapter reviews the methods that developed for (1) investigating the complexity and relationships of those processes that serve as developmental timers, (2) isolating timer mutants, (3) initiating rapid recapitulation, (4) initiating erasure and the subsequent program of dedifferentiation, and (5) stimulating simultaneous progress through dedifferentiation and redifferentiation. D. discoideum is employed as a system for studying the developmental regulation of gene expression, chemotaxis, cell interactions, cohesion, cytoskeleton, and a long list of other cell functions and components. Dictyostelium discoideum provides an excellent system, as for many unsolved problems in cellular, molecular, and developmental biology to invest timing regulation. First, because the developmental program includes an ordered, easily monitored, and highly reproducible sequence of morphogenetic stages, it lends itself to detailed investigations of the number, complexity, and dependencies of those processes which are rate-limiting for developmental stages. These processes are referred to as “developmental timers.” Second, because of the cellularity of Dictyostelium morphogenesis, developing cultures can be disaggregated and challenged to reinitiate development without an intermittent period of growth.