Von der Ecdysonkonzentration abhängige Genaktivitätsmuster in den Speicheldrüsenchromosomen von Chironomus tentans

[摘要] 1.1.InjectionofecdysoneintolastinstarlarvaeofChironomustentansinducesactivity(asindicatedbypuffing)oftwoloci(I-18-CundIV-2-B)inthesalivaryglandchromosomeswithinlessthan1hour.Thedependenceofthesizesofthesepuffs(asameasureofgeneactivity)ontheconcentrationofecdysoneinjectedisstudiedinthispaper.2.2.ThereactionthresholdforgeneI-18-Cliesataconcentrationof10−7μg,thatofgeneIV-2-Bataconcentrationof10−6μgofecdysonepermilligramlarvalweight.Bothpuffsincreasegraduallywithincreasinghormonedoses.Themaximalsizesarereachedatconcentrationsof10−2(I-18-C)and10−4(IV-2-B)μgecdysonepermilligramlarvalweight.Thus,thesizeofpuffI-18-Cdependsonthehormoneconcentrationinarangeofabout5,thatofpuffIV-2-Binarangeofabout2ordersofmagnitude.3.3.Thedurationoftheinducedgeneactivitiesdependsonthehormonedosesinjected.PuffI-18-Chasdisappeared8hoursafterinjectionof2×10−6and2×10−5μgofecdysone.Uptoadoseof2×10−3μg,areductionofgeneactivityisrecognizablebyadecreaseofpuffsize.PuffIV-2-Bhasoftendisappearedeven8hoursafterinjectionof2×10−4μgofecdysone.Thisisinagreementwiththelowersensivityofthislocus.ItisconcludedthattheactivitiesoflociI-18-CandIV-2-Bareunderpermanentcontroloftheconcentrationofecdysone.4.4.DuringnormalpupalmoltpuffIV-2-Bappears1to2dayslaterthanpuffI-18-C.Thisdifferencefromtheexperimentallyinducedmoltingisexplainablebythedifferentreactivitiesofthetwoloci.Itisconcludedthatduringthenormalmoltthetiterofecdysonerisesgraduallyandthattheactivitypatternofthesegenesisadjusteddependinguponthealteringhormonetiter.Theconcentrationofecdysoneinmoltinglarvaemaybeestimatedasfollows:youngprepupae10−7to10−5μg,prepupaeofmiddleageupto10−4or10−3μg,oldprepupae10−2μgofecdysonepermilligramlarvalweightorevenmore.

[学科分类] 生物科学（综合）