Differentiation of Dictyostelium discoideum mutant cells in a shaken suspension culture and the effect of cyclic AMP

Abstract

In Dictyostelium discoideum, 16 mutants in which cells differentiate into spores and stalk cells without normal morphogenesis were isolated. All these mutants are rapidly developing and capable of differentiating in a shaken suspension of phosphate buffer.The developmental kinetics of specific activities of enzymes in one of the mutants, HTY 1851, cultured in the suspension was compared with that in the parental strain, X2, developed on a solid surface. Most of the enzyme activities appeared much earlier and the peaks of the activities were lower in HTY1851 than X2, but the order or appearance of the activities was the same in both the strains cultured under the conditions described above. These results suggest that the biochemical steps in the development of the mutant in a shaken suspension are essentially the same as those of the parental strain X2 on a solid surface. It was also found that addition of cyclic AMP (2.5 X 10-5 M to 1 X 10-4 M) to the mutant cell suspension 6–8 h after the initiation of development induced an increase in the number of spores and the specific activities of some enzymes to values twice as high as those of an untreated control.