Konstanz, Wechsel und Typus der Determination und Differenzierung in Zellen aus männlichen Genitalanlagen von Drosophila melanogaster nach Dauerkultur in vivo

[摘要] 1.1.LarvalprimordiaofthemalegenitalimaginaldiskofDrosophilamelanogaster,whosecellsaredeterminedforformingspecificelementsofthegenitalapparatusandtheanalregion,werecultivatedforyearsintheabdomensofadultfemales.Inthismediumnodifferentiationofimaginalstructuresoccurs.2.2.Testfragmentsofthepermanentculturesweretransplantedbackintolarvae.Imaginaldifferentiationoccursonlyinthisfinalmetamorphosinghost.Ourtechniquemakesitpossibletotestatanydesiredmomentthereplicatingstateofdeterminationandthepotenciesfordifferentiationpresentinthecellculture.3.3.Startingwithsixindependentmainlines,wefollowedthedifferentiationinnumeroussubcultures.Thepresentreportdealswiththeresultsgainedfrom4139testimplants,whicharedistributedover55transfergenerations(Trg)cultivatedduringatwo-yearperiod.4.4.Theinitialstateofdeterminationispropagatedbycellheredityinnumeroussubcultureswithoutchange.Thedifferentiationremainsthereforeautotypic.Ourtechniqueoffragmentationleads,however,toasegregationofdifferentlydeterminedblastemas.5.5.Proliferatingpopulationsofcellswhichareautotypicallydeterminedfurnishregularlyallotypicdeterminedblastemas.Thisprocessiscalledtransdetermination.Itleadstoanlagesystemswhicharetypicalofotherimaginaldisks.6.6.Newlyestablishedallotypicblastemasmaybepropagatedbycellhereditywithoutfurtherchange,orpartsoftheiroffspringmayundergofurthertransdeterminationtowardotherallotypicprimordia.7.7.Ananalysisofthematerialshowsthatthereisatypicaldirectionandsequenceofthevarioustransdeterminations.Thus,atransdeterminationofthefirstorderleadsfromautotypicanal-plateblastemastoallotypichead(antennaeandpalpus)orleganlagen.Furthertransdeterminationsoftheseprimordialeadtowingcells,andfinallytothoraxblastemas.8.8.Eachstepofthetransdeterminationsequenceischaracterizedbyacertainprobability.Somestatesofdeterminationareeasilyreversible,whileforothersreversionshavebeenrarelyorneverobserved.9.9.Thefrequency(high,low,ornever)withwhichorganorbodypartshavebeenformedasaresultoftransdeterminationisreported.10.10.Notonlydotransdeterminationsleadfromtheblastemasofoneimaginaldisktotheanlagenofanotherdisk,butalsofromoneblastematoaneighboringoneofthesamedisk(region-specifictransdetermination).11.11.Transdeterminationisinterpretedasaprocessthatinvolvesthecontrolofgeneactivity.Ahypothesisisproposedwherebydifferencesinthedynamicsofcellproliferationcanleadtodiversegradesofdilutionofpreexistingcarriersofdetermination.Suchcarriersmightactaseffectorsofgenesystems.12.12.Homoioticmutantsandtheirphenocopies,aswellashomoiosisinregenerationarecomparedwiththetransdeterminationsofourcultures.Acommonbasisforallthesephenomenaisproposed.13.13.Onlyacursorydiscussionisgivenonanormotypicandatelotypicsubcultureswhicharosefromnormotelotypicblastemas.14.14.Theworkreportedhereprovidesfurtherinformationonthefollowingproblems:determinationasacharacterofmulticellularblastemasandasaqualityofsinglecells;homonomousarealizationandregionalizationinblastemas;andtheroleofsinglecellsinpatternformation.

[学科分类] 生物科学（综合）