The ultrastructural localization of DOPA-3H in differentiating amphibian melanophores grown in vitro☆
[摘要] Explantsoftrunkneuralcrestfromaxolotl(Ambystomamexicanum)embryosweregrownfor7daysinhangingdropcultures.Inthedifferentiatingmelanophores,theGolgiapparatusandrough-surfacedendoplasmicreticulum(RER)areprominentandwelldeveloped.Thecytoplasmisfurthercharacterizedbygroupsoffreeribosomesandextensivearraysofpolyribosomes,anirregularsystemofsmoothendoplasmicreticulum,yolkplatelets,lipochondria,mitochondria,microtubules,vacuoles,vesicles,andnumerouspigmentgranulesinvariousstagesofdevelopment.AlthoughsomenewlyformedpremelanosomesarefoundneartheGolgiandRER,mosthavenospecialtopographicrelationshiptoeitherorganelle.Seven-day-oldculturesweretreatedwithtritiated3,4-dihydroxyphenylalanine(DOPA-3H)andstudiedbymeansofelectronmicroscopicradioautography.Thespecificlocalizationofradioactivityinpremelanosomesshowsthatthisorganelleisthesiteofmelanogenesisindifferentiatingamphibianmelanophores.ThetimeatwhichthepremelanosomeisfirstabletoutilizeexogenousDOPAcoincideswiththetimeatwhichthedevelopinggranulecomestocontainthickenedfibrilswithperiodicsubstructure.Theearlierunpigmentedpremelanosomecontainingameshworkofthinfibrilsandsmallvesiclesdoesnotincorporateisotope.Duringthegenesisofthemelanosomethereisamorphologicallydistinctstageatwhichthepremelanosomeacquiresthecapacityformelaninsynthesisanddeposition.
[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]
