Analysis of an inducer of the amoebal-plasmodial transition in the Myxomycetes Didymium iridis and Physarum polycephalum

The nuclear reproductive cycle in the myxomycetes: a review

“…Ross (1967) using a heterothallic strain of Didymium iridis confirmed the general consensus arrived at by the earlier studies; and with others (Ross & Cummings 1970, Ross & Shipley 1973, Albert & Therrien 1985) went on to show that amoeboflagellates must first become competent before they can fuse and that competency required that the cells reach a minimum population density. Both Didymium iridis and Pysarum polycephalum mating type amoeboflagellate clones were grown separately (Shipley & Holt 1982) to the competency density before mixing, to demonstrate that both mating types must be competent before syngamy would occur and that competency involved the production of an extracellular inducer material released by the growing amoeboflagellates (Youngman et al 1977, Pallotta et al 1979, Nader et al 1984, Albert & Therrien 1985. Ross & Cummings (1970) also observed that the mixing of mating type clones after they had reached maximum competency, produced a rapid fusion of multiple amoeboflagellates that formed polyploid nuclei in large synctia.…”

Plasmodium development in the myxomycete Physarum polycephalum: genetic control and cellular events

“…Addition of partially purified inducer to cultures of apogamic cells advances the initiation of plasmodium formation (Nader et al, 1984). The same preparations also affect mating (see above), suggesting that the same inducer affects the acquisition of fusion competence in sexual development and initiation of apogamic development (Nader et al, 1984).…”

“…The proliferating amoebae secrete a chemical inducer and plasmodium formation is triggered when the inducer reaches a critical concentration in the local environment (Youngman e t al., 1977). Addition of partially purified inducer to cultures of apogamic cells advances the initiation of plasmodium formation (Nader et al, 1984). The same preparations also affect mating (see above), suggesting that the same inducer affects the acquisition of fusion competence in sexual development and initiation of apogamic development (Nader et al, 1984).…”

“…Dense cultures of amoebae can induce competence in overlying sparse cultures separated by 0.2 pm filters (Pallotta e t al., 1979;Shipley & Holt, 1982), suggesting that an extracellular inducer is responsible for the acquisition of fusion competence. Preliminary analyses suggest that this inducer may be a complex molecule that acts over a short range and decays quickly (Nader et al, 1984). Addition of partially purified inducer to mixtures of compatible amoebae advances the start of plasmodium formation (Nader et al, 1984).…”

“…Preliminary analyses suggest that this inducer may be a complex molecule that acts over a short range and decays quickly (Nader et al, 1984). Addition of partially purified inducer to mixtures of compatible amoebae advances the start of plasmodium formation (Nader et al, 1984).…”