Nonvitellogenic female sterile mutants and the regulation of vitellogenesis in Drosophila melanogaster☆

[摘要] Thegeneticandendocrineregulationofvitellogenesiswasinvestigatedbystudying18femalesterilemutationsthatdisruptthedevelopmentofnormalvitellogenicfollicles.Applicationsofexogenousjuvenilehormoneanalogandreciprocalovariantransplantsbetweenfliesofdifferentgenotypeswereemployedtoaccomplishourfirsttwoobjectives:tofind(1)whetherthemutationblockeddevelopmentoftheovarydirectly,and(2)whetherthemutationalteredthehormonalmilieu.In15ofthemutantsthedevelopmentaldefectwaslocalizedtotheovary,butintheother3theovarywascompetenttorespondtoapermissiveenvironment.Theinternalmilieuofthesethreemutants(ap4,fs(3)A1,fs(2)A18)wasunabletoprovokenormaldevelopmentinwild-typeovaries,suggestingthatthesemutationscauseendocrinedefects.Ourthirdobjectivewastofindwhetheranendocrineorganwasitselfdefectiveinanyofthesemutants.Thecorpusallatumfromtwoofthemutantswasunabletoprovokevitellogenesisinisolatedwild-typeabdomens,butcorporaallatafromwild-typefemalesorfromothermutantswereabletopromotematurationofovarianfolliclesinisolatedabdomens.Ourfourthobjectivewastofindwhetheranyofthemutantswereabletoproduceyolkproteins.Immunoelectrophoresisofflyhemolymphdemonstratedthatinallmutantstestedvitellogeninswerefoundintheblood.Theseexperimentspermitfourmainconclusions.First,theyidentifythefirstDrosophilamutantsinwhichanendocrineglandisshowntobeintrinsicallydefectiveduringadulthood.Second,theyshowthattheproductionofmorphologicallynormallateprevitellogenicfolliclesisnotrequiredfortheinductionofvitellogeninsynthesisandsecretion.Third,theyshowthatjuvenilehormonecancauseovarianfolliclestosequesteryolkinmutantflies.Andfinally,theyshowthatmutantswithdefectivecorporaallatastillsynthesizeandsecretevitellogenin.Takentogether,theseconclusionssuggestthatinDrosophilamelanogastertheuptakeofvitellogeninintofolliclesdependsupontheavailabilityofjuvenilehormone,butthatthesynthesisandsecretionofvitellogeninareindependentofbothnormalovariesandtotallynormalcorporaallata.

[学科分类] 生物科学（综合）