Commitment of hydra interstitial cells to nerve cell differentiation occurs by late S-phase☆

[摘要] Nervecellsinhydradifferentiatefromtheinterstitialcell,amultipotentstemcell.Decapitationelicitsasharpincreaseinthefractionoftheinterstitialcellscommittedtonervecelldifferentiationinthetissuewhichformsthenewhead.Toinvestigatewhenduringthecellcyclenervecellcommitmentcanbestimulated,hydrawerepulse-labeledwith[3H]thymidineattimesfrom18hrbeforeto15hrfollowingdecapitation;theresultingcohortsoflabeledinterstitialcellswereinthevariousphasesofthecellcycleatthetimeofdecapitation.Increasedcommitmenttonervecelldifferentiationwithinasinglecellcycle(≈24hr)wasobservedinthosecohortswhichwereatleast6hrbeforetheendofS-phase(12hr)atthetimeofdecapitation.Thelagtimerequiredfordecapitationtoproduceaneffectivestimulusfornervecelldifferentiationwasmeasuredbytransplantingthestemcellsfromtheregeneratingtissuetoaneutralenvironment.Followingdecapitation,3to6hrwererequiredforincreasednervecellcommitmenttobestabletosuchtransplantation.TheseresultssuggestthatinterstitialcellsmustbestimulatedbylateS-phasetobecomecommittedtoundergonervecelldifferentiationfollowingthesubsequentmitosis.However,whenheadregenerationwasreversedbygraftinganewheadontotheregeneratingsurface,nervecelldifferentiationbysuchcommittedstemcellswasgreatlyreduced.Thisindicatesthatanappropriatetissueenvironmentisrequiredforcommittedinterstitialcellstocompletethenervecelldifferentiationpathway.

[学科分类] 生物科学（综合）