Sequential gene activation by ecdysone in polytene chromosomes of Drosophila melanogaster,: III. Consequences of ecdysone withdrawal☆
[摘要] EcdysoneinducesasequenceofchangesinpuffingactivityofthepolytenesalivaryglandchromosomesofDrosophilamelanogaster.Inthecontinuouspresenceofecdysonethissequencetakesabout12hrtocomplete.Salivaryglandswereincubatedinthepresenceofecdysoneforvarioustimesandthentransferredtohormone-freemediumtostudytheeffectsofthehormone'sremovalonthesequenceofpuffingactivities.Theearlyecdysone-inducedpuffsimmediatelyregressonremovalofhormone.Theycanbefullyreinducedifexposedtohormoneagain,butonlyiftheinitialperiodofexposuretothehormonewas2hrorless;withlongerperiodsofinitialexposuretheearlypuffsbecomeprogressivelyrefractorytoreinduction.Thisprocessisinhibitedbycycloheximide.Agroupofthelatepuffsmaybeinducedprematurelybyremovalofthehormone—theextentoftheirprematureinductioniscorrelatedwiththesizeoftheearlypuffsduringtheperiodofecdysoneexposure.Ecdysoneinhibitstheprematureinductionoftheselatepuffs.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
