Trunk lateral cells are neural crest-like cells in the ascidian Ciona intestinalis: Insights into the ancestry and evolution of the neural crest

摘要

Neuralcrest-likecells(NCLC)thatexpresstheHNK-1antigenandformbodypigmentcellswerepreviouslyidentifiedindiverseascidianspecies.Hereweinvestigatetheembryonicorigin,migratoryactivity,andneuralcrestrelatedgeneexpressionpatternsofNCLCintheascidianemCionaintestinalis/em.HNK-1expressionfirstappearedataboutthetimeoflarvalhatchingindorsalcellsoftheposteriortrunk.Inswimmingtadpoles,HNK-1positivecellsbegantomigrate,andaftermetamorphosistheywerelocalizedintheoralandatrialsiphons,branchialgillslits,endostyle,andgut.CleavagearrestexperimentsshowedthatNCLCarederivedfromtheA7.6cells,theprecursorsoftrunklateralcells(TLC),oneofthethreetypesofmigratorymesenchymalcellsinascidianembryos.Incleavagearrestedembryos,HNK-1positiveTLCwerepresentonthelateralmarginsoftheneuralplateandlaterbecamelocalizedadjacenttotheposteriorsensoryvesicle,astagingzonefortheirmigrationafterlarvalhatching.TheemCiona/emorthologuesofsevenofsixteengenesthatfunctioninthevertebrateneuralcrestgeneregulatorynetworkareexpressedintheA7.6/TLClineage.Thevertebratecounterpartsofthesegenesfunctiondownstreamofneuralplateborderspecificationintheregulatorynetworkleadingtoneuralcrestdevelopment.TheresultssuggestthatNCLCandneuralcrestcellsmaybehomologouscelltypesoriginatinginthecommonancestoroftunicatesandvertebratesandsupportthepossibilitythataputativeregulatorynetworkgoverningNCLCdevelopmentwasco-optedtoproduceneuralcrestcellsduringvertebrateevolution./p/div