Plasticity in Zebrafish hox Expression in the Hindbrain and Cranial Neural Crest

摘要

Theanteriorndash;posterioridentitiesofcellsinthehindbrainandcranialneuralcrestarethoughttobedeterminedbytheiremHox/emgeneexpressionstatus,buthowandwhencellsbecomecommittedtotheseidentitiesremainunclear.Hereweaddressthisinzebrafishbycelltransplantation,totestplasticityinemhox/emexpressioninsinglecells.Wetransplantedcellsalone,orinsmallgroups,betweenhindbrainrhombomeresorbetweentheneuralcrestprimordiaofpharyngealarches.Wefoundthattransplantedcellsregulatedemhox/emexpressionaccordingtotheirnewenvironments.Thedegreeofplasticity,however,dependedonboththetimingandthesizeofthetransplant.Atlaterstagestransplantedcellsweremorelikelytobeirreversiblycommittedandmaintaintheiremhox/emexpression,demonstratingaprogressivelossofresponsivenesstotheenvironmentalsignalsthatspecifysegmentalidentities.Individualtransplantedcellsalsoshowedgreaterplasticitythanthoselyingwithinthecenteroflargergroups,suggestingthatacommunityeffectnormallymaintainsemhox/emexpressionwithinsegments.Wealsoraisedexperimentalembryostolarvalstagestoanalyzetransplantedcellsafterdifferentiationandfoundthatneuralcrestcellscontributedtopharyngealcartilagesappropriatetotheanteriorndash;posteriorlevelofthenewcellularenvironment.Thus,consistentwithmodelsimplicatingemhox/emexpressionincontrolofsegmentalidentity,plasticityinemhox/emexpressioncorrelateswithplasticityinfinalcellfate./p/div