Concanavalin A as a peripherally acting inhibitor of thyroxin-mediated metamorphosis in amphibians☆
[摘要] StimulatedbyreportsthatConcanavalinA(ConA),aplantproteinandlectinfromjackbean,hasaninhibitoryeffectonthyroidactivationinducedbythyrotropin,wesetouttotestwhetherConAinhibitsthyroidactiononhormone-sensitivetargettissuesinamphibians.Wenotedthatpremetamorphictadpolesinjectedwith0.15mlofthyroxin(T40.24μM)respondedbyacceleratingmetamorphicchangeasindicatedbyprecociousdisappearanceofthetail,andappreciablegrowthofthehindlimbsandchangesinmouth-partmorphology.TadpolesgivenaninjectionofthyroxinimmediatelyfollowedbyaninjectionofConA(9.6μM)showednosuchmetamorphicchanges.InthesecondseriesofexperimentstailfindiscsobtainedfrompremetamorphictadpoleswhenplacedinculturessupplementedwithT4(0.24μM)hadcompletelyshrunkwithin96hr.TailfindiscsthatwereraisedinvitroinmediumcontainingConAaswellasthyroxinfailedtoregress.Inthethirdseriesofexperimentstaildiscswereinitiallyculturedinmediumcontainingthyroxinandtransferredwithin48hrtomediumcontainingConA.WhenConAwasaddedafterthis48-hrexposuretothyroxinitwasnolongereffectiveinpreventingtailfindiscresorption.Weconcludetentatively(1)thatConAisaperipheralinhibitorofthyroxinand(2)thisitsomehowbindstothetissueorinteractswiththyroxinrenderingitineffectivebeforethehormonehasachancetoact.Thesignificanceoffindingaperipherallyactiveinhibitorofthyroidhormoneforstudiesofmechanismofactionofthishormoneondevelopmentanddifferentiationofhormone-sensitivetargetstructuresisobvious.
[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]
