Development of the ciliature of Tetrahymena thermophila: II. Spatial subdivision prior to cytokinesis☆
[摘要] ThecellsurfaceofTetrahymenathermophilaismadeupofananteriorregioninwhichvirtuallyallbasalbodiesofciliaryrowsareciliated,andtheremainderinwhichciliatedandunciliatedbasalbodiesarefairlyirregularlyinterspersed.Thispatternpersiststhroughinterfissiondevelopmentuntilthestageofappearanceoftheequatorialringofgapsintheciliaryrowsthatmarksthefissionzone.Theciliationpatternthenbecomessubdivided,inlargepartthroughtherapidciliationofcontiguousbasalbodieslocatedposteriortothefissionzone.Weinterpretthisprocessasawaveofciliationofpreexistingbasalbodiesthatpropagatesposteriorlyfromthesiteofthefissionzone.Thelocation,extent,andtimingoftheciliationprocessarethesameininvertedasinnormallyorientedciliaryrows,inspiteofthefactthatininvertedrowsthevisiblefissionzonegapistardilyformedandthelocalconfigurationofciliaturearoundthisgapisabnormal.Theputativeciliationwavethusdoesnotdependdirectlyuponthelocalmanifestationsofthefissionzone.However,inacell-division-arrestmutant,cdaA1,analyzedunderconditionsinwhichformationoffission-zonegapsispermanentlypreventedinsomeciliaryrowsbutnotinall,itisfoundthattheciliationpatternbecomessubdividedinthoseciliaryrowsthatexpressfission-zonegapsandfailstobecomesubdividedinneighboringrowsthatfailtomanifestgaps.Weinterpretthiscombinationoffindingstoindicatethatasignallocalizedatthecellequatorinitiatesasetofpolarizeddevelopmentaleventsthatsimultaneouslycreateanddemarcatetwocellularfieldswithinwhatwaspreviouslyone.Wefurthersuggestthatthecharacteristictandemcelldivisionpatternofciliatesisfundamentallyaprocessofsegmentation,whichmightinvolvemechanismsofgradientsubdivisionanalogoustothosetakingplaceduringsegmentationofinsectsandothermulticellularorganisms.
[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]
