title: Proportionality in the pattern of differentiation of the cellular slime mould Dictyostelium discoideum and the time of its determination.
abstract: A quantitative measure of the proportionality of the pattern of cell differentiation is obtained by separating populations of fruiting bodies into stalks and spores and determining the ratio of their dry weights. The effect of incubation temperature on the proportion of a population which becomes stalk cells is determined. The time of determination of this proportion is then indicated by the time in the developmental sequence at which a temperature shift fails to alter it. The results show that the temperatures of growth, aggregation and migration have no effect on the pattern of differentiation and that temperature alterations during early culmination alter the pattern of differentiation. This result demonstrates that the pattern of differentiation is not determined during the migrating slug stage, and it is suggested that the axial inhomogeneities seen in the slug are not directly related to the terminal pattern of differentiation of the fruiting body as has been previously suggested.
mesh_terms: D002454:Cell Differentiation; D009235:Myxomycetes / Q000166:cytology*; D013696:Temperature; D013997:Time Factors