The control of growth and differentiation of the wing imaginal disks of Manduca sexta

摘要

Duringthelarvalfeedingperiod,thegrowthofthewingimaginaldisksofLepidopteraisdependentoncontinuousfeeding.Feedingandnutritionexerttheireffectviathesecretionofbombyxin,thelepidopteraninsulin-likehormone.Whenlarvaestopfeedingandenterthewanderingstageinpreparationformetamorphosis,thecontrolofimaginaldiskgrowthbecomesfeedingandnutrition-independent.Growthofthewingimaginaldisksofnon-feedingwanderingstageemManducasexta/emcanbestoppedbyremovalofthebrain,indicatingthatabrain-derivedfactorisrequiredforcontinueddiskgrowth.Isolatedwingdiskgrowtheminvitro/emrequiresboth20-hydroxyecdysone(20E)andeitherbrainextractorbombyxintoachievenormalgrowth.emInvitro/em,brainextractsandsyntheticbombyxinhavelittleornoeffectinstimulatingdiskgrowth,buttheygreatlyenhancetheeffectof20E,indicatingthat20Eandbombyxinactsynergisticallytomodulategrowthoftheimaginaldisk.Brainextractandbombyxininduceasuiteofinsulin-responseeventsinculturedwingdisks,whichindicatethatbombyxinand20Eactthroughseparateandsynergisticpathways.Thedose-responseto20Ereachesaplateauatabout0.1nbsp;μg/ml.Trachealdifferentiationofthewingdiskscanbeinducedtoinitiateeminvitro/embyalowconcentrationof20E,whereashigherconcentrationsof20Eonlystimulategrowth./p/div