The Development of Three Identified Motor Neurons in the Larva of an Ascidian, Halocynthia roretzi

Developmental Biology

Fumihito Ono¹  Yasushi Okamura¹  Toshiaki Okada¹  You Katsuyama¹ 

[1] Molecular Neurobiology Group, Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 6th, Higashi 1-1-1, Tsukuba, Ibaraki, 305-8566, Japan

关键词: neural tube;    ion channel;    dominant negative;    swimming behavior;    LIM homeodomain protein;    tadpole larva;    ascidian;   

DOI  :  10.1006/dbio.2002.0585

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Thegenerationofdistinctclassesofmotorneuronsunderliesthedevelopmentofcomplexmotilebehaviorinallanimalsandiswellcharacterizedinchordates.Recentmolecularstudiesindicatethattheascidianlarvalcentralnervoussystem(CNS)exhibitsanteroposteriorregionalizationsimilartothatseeninthevertebrateCNS.Toextendtheunderstandingaboutthediversityofmotorneuronsintheascidianlarva,wehaveidentifiedthenumber,position,andprojectionofindividualmotorneuronsinHalocynthiaroretzi,usingagreenfluorescentproteinunderthecontrolofaneuron-specificpromoter.Threepairsofmotorneurons,eachwithadistinctshapeandinnervationpattern,wereidentifiedalongtheanteroposterioraxisoftheneuraltube:theanteriorandposteriorpairsextendtheiraxonstowarddorsalmusclecells,whereasthemiddlepairprojecttheiraxonstowardventralmuscle.Overexpressionofadominant-negativeformofapotassiumchannelinthesecellsresultedinparalysisontheinjectedside,thusthesecellsmustconstitutethemajorpopulationofmotorneuronsresponsibleforswimmingbehavior.Limclasshomeoboxgeneshavebeenknownascandidategenesthatdeterminesubtypesofmotorneurons.Therefore,theexpressionpatternofHrlim,whichisaLimclasshomeoboxgene,wasexaminedinthemotorneuronprecursors.AllthreemotorneuronsexpressedHrlimatthetailbudstage,althougheachdown-regulatedHrlimatadifferenttime.MisexpressionofHrlimintheepidermallineageledtoectopicexpressionofTuNa2,aputativevoltage-gatedchannelgenenormallyexpressedpredominantlyinthethreepairsofmotorneurons.Hrlimmaycontrolmembraneexcitabilityofmotorneuronsbyregulatingionchannelgeneexpression.

【 授权许可】

Unknown