Roundabout gene family functions during sensory axon guidance in the drosophila embryo are mediated by both Slit-dependent and Slit-independent mechanisms

摘要

emroundabout(robo)/emfamilygenesplaykeyrolesinaxonguidanceinawidevarietyofanimals.Wehaveinvestigatedtherolesoftheemrobo/emfamilymembers,emrobo,robo2,/emandemrobo3,/emintheguidanceofsensoryaxonsintheemDrosophila/emembryo.Inemrobosupminus;/minus;/sup,slitsupminus;/minus;/sup,/emandemrobosupminus;/+/supslitsupminus;/+/sup/emmutants,lateralclustersensoryneuronsmisprojecttocellsandaxonsinthenearbyventral'(v')cluster.Thesephenotypes,togetherwiththenormalexpressionpatternofSlitandRobo,suggestthatSlitligandsecretedfromtheepidermisinteractswithRoboreceptorsonlateralclustersensorygrowthconestolimittheirexplorationofnearbyattractivesubstrates.Themostcommonsensoryaxonphenotypeseeninemrobo2/emsupminus;/minus;/supmutantswasmisprojectionofdorsalclustersensoryaxonsawayfromtheirnormalgrowthsubstrate,thetransverseconnectiveofthetrachea.emslit/emappearstoplaynoroleinthisaspectofsensoryaxongrowth.Robo2isexpressed,notonthedorsalsensoryaxons,butonthetransverseconnective.Theseresultssuggestanovel,non-cell-autonomousmechanismforaxonguidancebyemrobo/emfamilygenes:Robo2expressedonthetracheaactsasanattractantforthedorsalsensorygrowthcones./p/div