Colchicine induces multiple axis formation and stalk cell differentiation in Dictyostelium discoideum

Colchicine is shown to have several effects on the development of the pseudoplasmodia of the cellular slime mould Dictyostelium discoideum At concentrations of 0·01 M and above culmination was prevented, while differentiation of cells into stalk cells occurred at the rear of cell masses. Essentially all cells transformed into stalk cells when slugs were left on colchicine agar for a long time. At concentrations of 0·01 M normal slug architecture was maintained while above 0·025 M pseudoplasmodia reorganized into multiple mounds. Each of these mounds developed an apparently normal discrete tip which was devoid of prespore cells as shown by immunofluorescent staining. The same effects were observed in growing cultures and in regulating slugs treated with colchicine. The data are consistent with the ideas that microtubules are involved in the maintenance of slug architecture and in the differentiation of stalk cells. The modes by which these intracellular structures may operate in these functions are discussed.