Analysis of development and growth in a mutant of Physarum polycephalum with defective cytokinesis

[摘要] CulturesofamoebaeofthemutantstrainATS23isolatedfromstrainCLdofPhysarumpolycephalumcontainmultinucleatecellsandcellswithincreasednuclearDNAcontent.PlasmodiaderivedfromATS23clonesshowabnormalmorphologyanddefectivesporulation.Allabnormalitiesareenhancedbyhighincubationtemperature(31°C).Geneticanalysissuggestedthatalltheabnormalitieswerecausedbyasinglemutation,denotedhts-23.Thekineticsofplasmodiumformationwerefollowedinculturesofapogamicamoebaecarryinghts-23andhts+(wildtype)respectively.Resultsindicatedthat,relativetowildtype,hts-23didnotincreasetherateofplasmodiumformation.Therewasevidencethat,inbothmutantandwild-typestrains,commitmenttoplasmodiumdevelopmentoccurredinuninucleatecells.Analysisofcellpedigreesbytime-lapsecinematographyindicatedthattheprimaryabnormaleventinculturesofhts-23amoebaewasfailureofcytokinesis;anapparentlycompletecleavagefurrowwasformedbutcellseparationfailed,resultinginabinucleatecell.Thiseventoccurredrandomlyinpedigreesinwhichthemajorityofdivisionswerecompletednormally;itsfrequencyincreasedduringincubationat31°C.Allotherabnormalitiesinhts-23amoebalculturescouldbeattributedtothisprimaryevent,assumingthatDNAsynthesiscontinuedintheabsenceofcytokinesisandthatthebinucleatecellsunderwenttheamoebaltypeof“open”mitosis,allowingthepossibilityofspindlefusion.Thisimpliesthattheacquisitionof“closed”mitosisisanessentialearlystepinplasmodiumdevelopment.

[学科分类] 生物科学（综合）