Dedifferentiation of the disaggregated slug cell of the cellular slime mold Dictyostelium discoideum.

Abstract

It was previously shown that differentiation of the prespore cell in the pseudoplasmodium (slug) of the cellular slime molds is characterized by the synthesis of a specific substance which is detectable by a heteroplastic antispore serum (Takeuchi, 1963). When a prespore cell which was already differentiated was disaggregated from a slug of Dictyostelium discoideum and was incubated in salt solution under a sparsely populated condition, it gradually lost its specific substance and dedifferentiated. The dedifferentiation proceeded without accompanying cell growth and was completed within 5 hr of incubation. This process was inhibited at a low temperature and also in the presence of cyclohexamide, actinomycin D, and cyclic AMP. The dedifferentiation was induced and proceeded at a normal rate in the absence of bacteria. When a disaggregated slug cell was incubated in the presence of bacteria, however, every prestalk and prespore cell was able to grow and underwent its first cell division after about 9–10 hr of incubation, and then multiplied with the generation time of 3 hr. The relationship between the dedifferentiation and the growth of a disaggregated slug cell was discussed.