The amoebal cell of Physarum polycephalum: Colony formation and growth☆

[摘要] TwostagesofcolonygrowthwereobservedduringmicroscopicstudiesofPhysarumpolycephalumamoebae.Duringthefirststage,“spreadinggrowth,”thecolonyiscomposedofdispersedsinglecells.Duringthesecondstage,“aggregategrowth,”mostoftheactivecellsinacolonyareaggregatedinaringatthecolonyboundary.Measurementsofcellmovementasafunctionofbacterialconcentrationindicatethat,duringbothspreadingandaggregategrowth,cellmovementsarenotaffectedbychangesinbacterialconcentrationbutthatthetransitionfromspreadingtoaggregategrowthoccursearlieronplateswithlowerbacterialconcentrations.Theseresultsindicatethatautonomouscharacteristicsoftheamoebaearemoreimportantforthedeterminationofcolonyformthanlocalvariationsintheconcentrationsofnutrients.Thegeneticdeterminationofcolonyformisdemonstratedbytheexistenceofmutantsthatdisplayspecificalterationsincolonymorphology.Becausetheaggregateringsofthesemutantsmoveatanincreasedrate,mutantclonesappearasvariantsectorsofwild-typecolonies.Theincreasedrateofmutantringmovementsuggeststhatthisselectionmethodmaybeausefultechniqueforisolatingmutantmyxamoebaewithdefectsinmovementandbehavior.

[学科分类] 生物科学（综合）