Differentiation and dedifferentiation can function simultaneously and independently in the same cells in Dictyostelium discoideum☆

[摘要] WhendevelopingculturesofDictyosteliumdiscoideumaredisaggregatedandmorphogenesisisreinitiated,cellsrecapitulatethestagestheyhadprogressedthroughpriortodisaggregationinafractionoftheoriginaltime.Ifdevelopingculturesaredisaggregatedandthecellsresuspendedinnutrientmedium,theyretainthiscapacityfor1.5hrandthensynchronouslyandrapidlyreverttotheslowtimingoflogphasecells.Lossofthecapacitytorecapitulatemorphogenesisrapidlyisreferredtoasthe“erasureevent.”Followingtheerasureevent,cellssystematicallylosedevelopmentallyacquiredfunctionsinadefinedtemporalsequenceofdedifferentiation.Cellswhichhavejustpassedthroughtheerasureeventcanbestimulatedtoreenterthedevelopmentalprogram,eventhoughtheystillpossessseveralaggregation-associatedfunctionsacquiredduringtheinitialdevelopmentalprogram.Inthisreport,wehavetestedwhethercellsstimulatedtoreenterthedevelopmentalprogramimmediatelyaftertheerasureeventprogressalongthesamerate-limitingpathwayleadingtoaggregationastheydidduringinitialdevelopmentandwhetherthisrate-limitingpathwaycanrunsimultaneouslywithandindependentlyofthesequenceofdedifferentiation.Resultsarepresentedwhichdemonstrate(1)thattheerasureeventresetstherate-limitingpathwayfordevelopmentbacktozeroandthaterasedcellsreenteringdevelopmentprogressalongthesamerate-limitingpathwayasnaivelogphasecells,(2)thatthelossofanaggregation-associatedfunctionlateinthesequenceofdedifferentiationiscompletelyblockedbytheadditionofcycloheximide,butnotcAMP,justpriortotheexpectedtimeofloss,and(3)thatdifferentiationanddedifferentiationcanfunctionsimultaneouslyandindependentlyinthesamecells,eventhoughtheformerleadstotheacquisitionandthelattertothelossofthesameaggregation-associatedfunctions(inthiscaseEDTA-resistantadhesionandcAMP-stimulatedmotility).

[学科分类] 生物科学（综合）