AUTO-ACTIVATION OF SPORE GERMINATION IN MUTANT AND WILD-TYPE STRAINS OF DICTYOSTELIUM-DISCOIDEUM

  • 1 January 1978
    • journal article
    • research article
    • Vol. 23  (93-9) , 153-166
Abstract
Freshly formed wild type D. discoideum spores are constitutively dormant, and thus require an activation treatment to germinate. Wild type spores may germinate without an activation treatment (autoactivate) after a period of aging (maturation) in the intact fruiting body. Mutants were isolated which autoactivate without the need for aging. Autoactivation of mutant and aged wild type spores appears to occur by identical mechanisms; thus the mutation may involve premature maturation. Autoactivation is mediated by autoactivator substances released from spores as they spontaneously swell. These factors are readily chromatographed, and elute from a Biogel P2 column in 3 peaks of activity. One activity peak appears only after spores begun to germinate. No autoactivator substances are released from heat activated spores. Autoactivation is sensitive to cycloheximide, and may result from altered spore permeability. Autoactivation is likely to be the mechanism of D. discoideum spore germination in nature.