Pacemaker mutants of Dictyostelium discoideum☆

[摘要] Inthispaper,IreportmeasurementsofthetimeintervalsbetweenaggregationwavesintwomorphogeneticmutantsofDictyosteliumdiscoideumNC-4.Themutantsbothhaveabnormalwaveperiodicityandtheirabnormalitiesareinterpretedintermsofdefectsinthecellularpropertieswhichunderliewavepropagation.Themainresultsareasfollows:1.(1)Thetwomutantseachhavethesamecategoriesofwaveformsaswild-typeDictyosteliumdiscoideumNC-4(concentricringandspiralwaves).Thetwokindsofwaveformshavecharacteristictemporalintervalsinthewild-typeandmutantstrains.2.(2)Inthemutant91A,concentricringandspiralwavesresembleequivalentwild-typewavesintheirtemporalperiodicity,butthemutanthasahighproportionofspiralwaves(60%ascomparedto16%inNC-4).Thisabnormalityisshowntobedueatleastpartlytoalowrateofemergenceofautonomoussignalingcompetencein91Acellsduringearlyaggregation.3.(3)ThemutantFr17hasnormalspiralwavesbutabnormalconcentricringwaves.TheconcentricringwavesofFr17areaperiodicandseparatedbyirregularlysequencedintervalsbetweenabout3and40minlong.ThoseofNC-4areusuallyeitherapproximatelyperiodic,with5-or10-minperiodicityorareseparatedbysteadilydecreasingintervalsbetweenand7and2.5min(Durston,1974).IsuggestthatFr17lackstwocellpropertiesmanifestedinNC-4(periodicandcontinuousautonomoussignaling)andinsteadhasanewproperty(aperiodicautonomoussignaling).

[学科分类] 生物科学（综合）