Factors controlling prespore cell differentiation in Dictyostelium discoideum: minute amounts of differentiation-inducing factor promote prespore cell differentiation.
Amoebae of strain V12M2 differentiate efficiently into prespore cells without cell contact in a salt solution containing cAMP, if the pH of the medium is maintained suitably acidic using a restricted buffer [31]. Under such conditions, most cells differentiate into prespore cells at pH 5.2. Using this developmental system, the elements controlling prespore-cell differentiation were analyzed. First, the dependence on cell density was examined. At a very low density (10(2) cells/cm2), most cells did not differentiate. As the density was increased the proportion of prespore cells differentiating increased, reaching a maximum at 5 x 10(3) cells/cm2. Conditioned medium could mimic the effects of cell density on cell differentiation. These findings suggest the presence of factor(s) released into the medium which are involved in inducing prespore-cell differentiation. The conditioned medium was found to contain at least two prespore-inducing components; one is a novel factor(s) and the other is DIF, which has previous only been considered to repress prespore-cell differentiation. These findings were supported by experiments using a DIF-deficient mutant, HM44.
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Biological Laboratory, Kansai Medical University, Osaka, Japan.
D000818:Animals; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology*; D017077:Culture Media, Conditioned; D004013:Dicrocoelium / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006131:Growth Inhibitors / Q000494:pharmacology / Q000502:physiology*; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology / Q000502:physiology*
D017077:Culture Media, Conditioned; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines