DNA replication may be uncoupled from nuclear and cellular division in temperature-sensitive embryonic lethal mutants of Caenorhabditis elegans☆
[摘要] ThenuclearandDNAcontentsof18temperature-sensitiveembryoniclethalmutantsofCaenorhabditiseleganshavebeendeterminedatthetimeofarrest.Aftereachmutantwasshiftedtorestrictivetemperature,theembryonicarreststagewasrecordedbythenumberofnucleicountedinembryonicsquashesandasDNAnuclearequivalentsrecordedbyflowcytometry.Togetherthetwomethodscomplementedeachotherandprovidedqualitativeandquantitativeinformationconcerningnuclearnumber,DNAcontent,morphologicalstageofarrest,andpresenceofanucleateembryoniccells.ThearreststageformostoftheembryoniclethalmutantsdemonstratedtheirpotentialtocontinuenucleardivisionandDNAreplicationbeyondtheirrespectivetemperature-sensitiveperiods.Theseresultssuggestedthatthemutants'primarydefectdidnotresideonapathwaycloselycoupledtoDNAreplicationornucleardivision.Forexample,B65containedupto650DNAnuclearequivalentsbeyondtheendofitstemperature-sensitiveperiodatthe20-to30-cellstage.B65isofadditionalinterestbecauseitcontinuedDNAsynthesisbeyondthenormal550-cellstageandatthesametimefailedtoprogressbeyondthemorphogeneticperiod.ThepresenceofenlargednucleithatcontainedextraDNAdemonstratedthatDNAreplicationwasindependentofnuclearandcellulardivision.Forexample,B1andB244arrestedwith1to50and1to200nuclei,respectively.However,theybothcontained250to400nuclearequivalentsofDNA.Conversely,thepresenceofembryoniccellswithoutnucleisuggestedthatcelldivisionmayalsobeindependentofnucleardivisionornuclearmigration.Theenlargednuclearandanucleateembryoniccellswereobservedonlyinthosemutantsrequiringanormalparentalfunction.
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[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
