Pupal cuticle formation by Manduca sexta epidermis in vitro: Patterns of ecdysone sensitivity☆

[摘要] Duringthelarval-pupaltransformation,variousregionsoftheepidermisofManducasextalarvaehavepreviouslybeenfoundtorequiredifferentlengthsofexposuretotheprothoracicglandsinordertoformpupalcuticle.Todistinguishbetweenrequirementsfordifferingthresholdconcentrationsofecdysoneandthosefordifferingdurationsofexposuretoecdysone,wanderingstagelarvalepidermiswasculturedinGrace'smedium.Whenmostofthethicklarvalcuticlewasremoved,theepidermisrespondedtoconcentrationsofβ-ecdysoneof1.0μ/mlorgreaterfor4daysbyformingcystswhichlaterformedtannedpupalcuticle.Nofatbodyorproteinsupplementwasrequired.Whenthelarvalintegumentwasexplantedintact,similarrequirementsforcuticleformationandfortanningwerefound.Allregionsofthefifthabdominalsegmentrequiredsimilarconcentrationsofβ-ecdysone(0.4–0.6μg/ml)for4daysfor50%toformpupalcuticle,butgintrapepidermisrequiredtheleastexposuretoathresholdconcentrationofecdysone(1.5daysin0.9μg/ml).Theanteriordorsalintersegmentalregionrequiredabout0.5daylonger,followedbytheposteriorintersegmentalandthedorsalintrasegmentalregions.Thus,thedurationofexposureseemedmoreimportant.About1daylongerofexposuretoecdysonewasrequiredforsubsequenttanningofthenewcuticlethanforcuticleformation,yettanningofthecuticledidnotoccurwithprolongedexposuretoecdysone.

[学科分类] 生物科学（综合）