Studies of Early Stages of Differentiation of the Cellular Slime Mould Dictyostellium discoideum

• Published in: Journal of embryology and experimental morphology Vol. 67; pp. 181 - 193
• Main Authors: Sharpe, P T, Treffry, TE, Watts, D J
• Format: Journal Article
• Language: English
• Published: 01.01.1982
• Subjects: Dictyostelium discoideum
• ISSN: 0022-0752

Countercurrent distribution in a polymer, two-phase system has been used to study changes in the cell surface properties of amoebae of D. discoideum . Amoebae harvested during exponential growth in axenic culture and during the subsequent first six hours of development on Millipore filters were distributed as a single peak, However, the position of the peak changed during the period of early development which showed that changes in cell surface properties were occurring. At aggregation (8 h), the peak markedly broaderned, indicating considerable increase in cell surface heterogeneity amongst the amoebae, and heterogeneity was so great by 9-10 h that the amoebae distributed as two peaks, Amoebae from one peak were shown to be precursors of spores while amoebae from the other peak appeared to be precursors of stalk cells. Similarly, amoebae from the trailing and leading edges of the broad peak, formed from amoebae beginning to aggregate (8 h), were found to have different fates. Thus cell differentiation had been found at times of development prior to formation of aggregates having apical tips or anterior-posterior polarity and neither of these features of aggregates can be essential for initiation of cell differentiation. It is therefore concluded that differentiation is not initiated in D. discoideum in response to "positional information".