DNA synthesis in unfertilized sea urchin eggs can be turned on and turned off by the addition and removal of procaine hydrochloride☆

[摘要] Unfertilizedseaurchineggsturnonthymidinetransport,DNAsynthesisandthechromosomecycleinresponsetoprocainehydrochloride.Theratestowhichtheseprocessesactivatedependontheextracellularconcentrationofprocaine.RemovingprocaineturnsoffDNAsynthesisandthechromosomecycle,re-addingprocaineturnstheseprocessesononcemore.Thymidinetransportdoesnotturnoffafterprocaineremoval.Itremainsonattherateithadreachedatthetimeofprocaineremoval.Duringa12-hrperiod,unfertilizedeggsinprocainecompletefourS-phases,whilenormal,fertilizedembryoscompleteeight.TritiatedthymidineincorporationintoDNAisverylowinprocaine-treatedeggs.Thisisbecauseinprocainethethymidinetransportsystemisrelativelyinactivecomparedtothatoffertilizedeggs.ThedatasuggesteggsmaypossesshomeostaticmechanismsthatactivelysuppresstheDNAsyntheticpathwayandthechromosomecycle.ThissystemforturningonandoffDNAsynthesismayproveusefulinfurtheranalysesofthefactorscontrollingDNAsynthesisduringearlydevelopment.

[学科分类] 生物科学（综合）