首页> 外文期刊>Developmental biology >Ultrastructural characterization of surface specializations containing high-density acetylcholine receptors on embryonic chick myotubes in vivo and in vitro☆
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Ultrastructural characterization of surface specializations containing high-density acetylcholine receptors on embryonic chick myotubes in vivo and in vitro☆

机译:体内和体外胚胎雏鸡肌管上含有高密度乙酰胆碱受体的表面特化的超微结构表征☆

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Surfacespecializations(patches)onmyotubesfromlatissimusdorsimusclesofembryonicchickbetween10and15daysofincubationandon5-day-culturedchickthighmyotubeswerecharacterizedbyheavymetalstainsandthebindingofhorseradishperoxidase-labeled?±-bungarotoxin(HRP-?±-BTX)forthelocalizationofacetylcholinereceptors(AChR).Thespecializationsconsistedofslightlyraisedsurfaceridges(0.1to0.5??minwidth)andwiderregions(2a€“5??m)sometimescomposedofaseriesofthesmallerridges.Thespecializedzoneswerecharacterizedbyanexternalcoatingofamorphous,fine-texturedmaterial,considerablymoreextensivethanthesparse,developingbasementlaminaoccurringelsewhereonthesurface.Ontheinternalsurfaceandcoextensivewiththeexternallayer,densematerialwasappliedimmediatelyadjacenttotheplasmamembrane.Cytoplasmicmicrofilamentsandmicrotubulescameintocloseproximitytothesubmembranousdensity.HRP-?±-BTXbindingoccurredatspecializedregions,indicatingthepresenceofahighdensityofnicotinicAChRatthesesites.Notallofthespecializedregionsnortheentireextentofthebroaderpatchesboundtheconjugate.Allregionsbindingtheconjugate,however,hadassociatedspecializations.Reactivecoatedvesicleswereassociatedwithpatchregions,indicatingtheymaybeinvolvedinthetransportofreceptor-bearingmembraneandcoatmaterialtothesurface.ThespecializedregionsbindingHRP-?±-BTXwereusuallywidelyseparatedonuninnervatedsurfaces.Reactivepatcheswereinvariablypresentatsitesofnerve-musclecontactinvivo.Inculturedmyotubes,largereactivepatchesweremoreabundantandmoreextensivethaninvivo.Theseregionscorrespondtothea€?hotspotsa€?observedatthelight-microscopiclevel.Reactivepatchesweremostabundantonthelateralandbasalsurfacesofcells,oncellprocesses,andwherecellscontactedthesubstrateorothercells.ThesestudiesshowthatexternalandinternalmembranespecializationsareassociatedwithahighdensityofAChRintheabsenceofinnervation.ConstituentsofthesespecializationsmaybeinvolvedinthelocalizationorpositioningofahighdensityofAChRatthesesitesorcontaincomponentswhichestablishtheseregionsaspreferentialsitesofrecognitionorcontactbythenerve.
机译:Surfacespecializations(补丁)onmyotubesfromlatissimusdorsimusclesofembryonicchickbetween10and15daysofincubationandon5天culturedchickthighmyotubeswerecharacterizedbyheavymetalstainsandthebindingofhorseradishperoxidase标记?±银环蛇毒素(HRP-?±-BTX)forthelocalizationofacetylcholinereceptors(乙酰胆碱受体).Thespecializationsconsistedofslightlyraisedsurfaceridges(0.1to0.5 ?? minwidth)andwiderregions(2A€“5 -4米)sometimescomposedofaseriesofthesmallerridges。 Thespecializedzoneswerecharacterizedbyanexternalcoatingofamorphous,细texturedmaterial,considerablymoreextensivethanthesparse,developingbasementlaminaoccurringelsewhereonthesurface.Ontheinternalsurfaceandcoextensivewiththeexternallayer,densematerialwasappliedimmediatelyadjacenttotheplasmamembrane.Cytoplasmicmicrofilamentsandmicrotubulescameintocloseproximitytothesubmembranousdensity.HRP-?±-BTXbindingoccurredatspecializedregions,indicatingthepresenceofahighdensityofnicotinicAChRatthesesites.Notallofthespecializedregionsnortheentireextentofthe broaderpatchesboundtheconjugate.Allregionsbindingtheconjugate,然而,hadassociatedspecializations.Reactivecoatedvesicleswereassociatedwithpatchregions,indicatingtheymaybeinvolvedinthetransportofreceptor-bearingmembraneandcoatmaterialtothesurface.ThespecializedregionsbindingHRP-?±-BTXwereusuallywidelyseparatedonuninnervatedsurfaces.Reactivepatcheswereinvariablypresentatsitesofnerve-musclecontactinvivo.Inculturedmyotubes,largereactivepatchesweremoreabundantandmoreextensivethaninvivo.Theseregionscorrespondtothea€?hotspotsa€?observedatthelight-microscopiclevel.Reactivepatchesweremostabundantonthelateralandbasalsurfacesofcells,oncellprocesses,andwherecellscontactedthesubstrateorothercells.ThesestudiesshowthatexternalandinternalmembranespecializationsareassociatedwithahighdensityofAChRintheabsenceofinnervation.ConstituentsofthesespecializationsmaybeinvolvedinthelocalizationorpositioningofahighdensityofAChRatthesesitesorcontaincomponentswhichestablishtheseregionsaspreferentialsitesofrecognit离子或神经接触。

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