Biological and molecular correlates between induced dedifferentiation and spore germination in Dictyostelium

When developing cultures of Dictyostelium discoideum are disaggregated at any time prior to cell wall formation and challenged to reinitiate development, amoebae will progress through the original sequence of morphogenetic stages, but the second time through they will do so in roughly one-tenth the original time, a process known as 'rapid recapitulation'. However, if disaggregated cells are suspended in nutrient medium, they enter a program of dedifferentiation during which they lose the capacity to rapidly recapitulate after an 80 minute lag period in a process known as 'erasure'. Here we show that cells that have completed the morphogenetic program and emerge from spore coats in the process of germination have also erased. In addition, the germination-specific 270 gene family is expressed during induced dedifferentiation in a unique fashion, and a germination-defective mutant exhibits a dramatic delay in erasure without concomitant defects in the program of gene regulation accompanying induced dedifferentiation. These results suggest for the first time that induced dedifferentiation and spore germination share some common processes in converting cells from a developmental to vegetative state.