Time of onset and selective response of chondrogenic core of 5-day chick limb after treatment with 6-aminonicotinamide☆

[摘要] Exposureofthechickembryotothenicotinamideanalog,6-aminonicotinamide(6-AN),causesspecificchangesinchondrogeniccellsthatresultinlimbdeformity.AutoradiographyhasfurtherdelineatedthesechangesandrelatesthemtoalteredutilizationofmolecularprecursorsofcartilagematrixandDNA.With35SO4tomonitorsynthesisofglycosaminoglycan,itwasshownthat,at6hrandpersistinguntil24hraftertreatment,6-ANinhibitedutilizationofsulfatebycellsinthechondrogeniccorewhilehavingnodetectableeffectoncellsinthechondrogenicperiphery.Similarly,6-ANsuppressedincorporationof[3H]thymidineintocorecellswhilehavingnoeffecttoaslightenhancementeffectonchondrogenicandnonchondrogeniccellssurroundingthecore.Theseobservationssupporttheviewthat,inresponseto6-AN-inhibitedNAD(P)-dependentreactions,limbchondrogeniccells(CORE)ceasetoproducematrixglycosaminoglycan,ceasetosynthesizeDNA,andultimatelysuccumb.Conversely,presumablyasaresultofmoreefficientenergyproductionbecausetheylieclosertoavascularsupplyofoxygen,cellsinthechondrogenicperipherywithstandtheteratogenicinsultandcontinueproliferatingtobecomethesourcewheresubsequentpartialrepairofthelimboccurs.

[学科分类] 生物科学（综合）