Specificity of cell-cell interactions in sea urchin embryos: Appearance of new cell-surface determinants at gastrulation☆

[摘要] Studiesonnormalandhybridseaurchinembryosshowthat,beginningatgastrulation,hybridcellsexpresscell-surfaceantigensspecifictobothspecies.Theappearanceoftheseantigensisshowntobecorrelatedwithachangeintheadhesivespecificityofhybridcells:Beginningatgastrulation,hybridcellsrecognizeandadheretoembryoniccellsofbothnormalgenotypes.Priortogastrulation,hybridcellsadheretocellsofthematernalgenotypeonly.Twoadhesionassaysdemonstratetheseadhesivepreferences.(i)Whencellaggregatesareplacedtogetherinadish,Lytechniusaggregatesfusetogether,andTripneustesaggregatesfusetogether,butaggregatesofthetwospeciesdonotfusewitheachother.Hybridcellaggregates,iftheyarepastthebeginningofgastrulation,fusetobothTripneustesandLytechinusaggregates.(ii)Inacollectionassay,midgastrulacellsofthehybridembryosarecollectedatahighratetoaggregatesofeitherspecies.Pregastrulahybridcellscollectatahighratetoaggregatesofthematernalspeciesonly.Thischangeinadhesivepreferenceistemporallycorrelatedwiththeappearanceofnewcellsurfaceantigens.AntiserumwaspreparedinrabbitsagainstmembranesfromLytechinusgastrulae.Indirectimmunofluorescencetestsshowthathybridcellsofthecross(T♀×L♂)expressLytechinus-specificantigensatthecellsurfacebeginningatgastrulation.Furthermore,anapparentrelationshipbetweenthenewcell-surfaceantigensandadhesionexistsinthatLytechinuscelladhesionisinhibitedspecificallyafterbindingFabfragmentsoftheLytechinusantiserum.TheantiserumhasnoeffectonTripneustesadhesion.TheLytechinusadhesion-inhibitingactivitycanberemovedbyabsorptionoftheantiserumwithLytechinuscells.

[学科分类] 生物科学（综合）