Drosophila embryonic neuroblasts in culture: Autonomous differentiation of specific neurotransmitters

摘要

Isolatedneuroblastsfromgastrula-stageDrosophilaembryosdivideanddifferentiateinvitrotoproduceclonallyderivedclustersofneurons.Bothserotoninanddopamineareexpressedwithintheseculturesinpatternsthataresimilartotheirdistributionsinvivo.Clusterscontainingserotonergicneuronsaregenerallydistinctfromthosewithdopaminergicneurons,suggestingthatdifferentneuroblastsproduceneuronswiththesephenotypes.Theappearanceofeachtransmittercorrelateswithtranscriptionofdopadecarboxylaseinthetransmitter-positivecells.Thedevelopmentalprogramleadingtotheappearanceofeitherserotonergicordopaminergicneuronsisdifferentforeachtransmittertype.Thus,serotonergiccellsareprogenyofearlyneuroblastdivisions,whereasdopaminergicsarisethroughoutthelineage.Inhibitionofcelldivision,butnotnucleardivision,withcytochalasinBdemonstratesthattheexpressionoftheserotoninphenotyperequiresadeterminednumberofDNAreplications.Theseexperimentsestablishthatneuroblasts,assoonastheyareformedduringearlygastrulationeventsinDrosophila,arealreadydeterminedforthesubsequentexpressionoftransmitterphenotype.