Microcyst formation in the plasmodial slime moldDidymium iridis

Ultrastructural changes in the myxamoebae of Physarum polycephalum in response to a microcyst-inducing concentration of mannitol

“…Acid phosphatase activity has been demonstrated in certain large vacuoles of myxamoebae by Aldrich and Reiskind (1982). Raub and Aldrich (1982) suggested that the ruthenium red positive contents of the vacuoles reported by Turner and Johnson (19750) were in fact extracellular and the vacuoles themselves invaginations of the plasma membrane as ruthenium red does not enter undamaged cells. However, Luft (197 1) did indicate that ruthenium red may infiltrate certain cell types and the general increase in contrast of the myxamoebae indicates that this is what occurs in this case.…”

“…Myxamoebae have been induced to encyst by starvation, both by nonrenewal of media (Turner and Johnson 1975a) and by transfer to a basal salts medium (Henney and Chu 1977). More recently Raub and Aldrich (1982) reported rapid and synchronous microcyst formation in Didymiurn iridis, another species of acellular slime mould, by transfer of agar-grown myxamoebae to 10 mM phosphate buffer at pH 6. The addition of high concentrations of carbohydrates to the growth medium has also been used to induce encystment, mannitol having been found to be the most effective of these (Haars et al 1979).…”