Abstract
Ascension of the cell mass during culmination was observed to be temperature-sensitive in strain HH31 of the cellular slime mold Dictyostelium discoideum. A sequence of additional developmental abnormalities was also observed both preceeding and succeeding culmination. Slugs reared at the restrictive temperature (27 degrees C), in contrast to those reared at the permissive temperature (22 degrees C), were deficient in the expression of six prespore markers and elevated in the production of four prestalk markers. Following attempted culmination at the restrictive temperature, the majority of cells were stalk cells according to fluorescence, phase contrast, electron microscopic, biochemical, and plating efficiency criteria. These findings were correlated with a general diminution of staining of slug cell Membrane extracts on polyacrylamide gels with FITC-wheat germ agglutinin. The effect of the higher temperature was readily reversible prior to terminal differentiation. An interdependence of several of the changes was suggested by the observation that in two derivative strains the temperature-dependence of these changes was coordinately altered. In summary, a large fraction of the slug cells of HH31 appear to be temperature-dependent in their choice of pathways of cell differentiation, this change is related to a modification of the cell surface, and the choice made in the slug is remembered by cells as they terminally differentiate.
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