Genetic analysis of a Drosophila neural cell adhesion molecule: interaction of fasciclin I and Abelson tyrosine kinase mutations

Cell. 1990 Feb 23;60(4):565-75. doi: 10.1016/0092-8674(90)90660-7.


Drosophila fasciclin I is a homophilic cell adhesion molecule expressed in the developing embryo on the surface of a subset of fasciculating CNS axons, all PNS axons, and some nonneuronal cells. We have identified protein-null mutations in the fasciclin I (fas I) gene, and show that these mutants are viable and do not display gross defects in nervous system morphogenesis. The Drosophila Abelson (abl) proto-oncogene homolog encodes a cytoplasmic tyrosine kinase that is expressed during embryogenesis primarily in developing CNS axons; abl mutants show no gross defects in CNS morphogenesis. However, embryos doubly mutant for fas I and abl display major defects in CNS axon pathways, particularly in the commissural tracts where expression of these two proteins normally overlaps. The double mutant shows a clear defect in growth cone guidance; for example, the RP1 growth cone (normally fas I positive) does not follow its normal path across the commissure.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Axons / physiology
  • Cell Adhesion Molecules, Neuronal / genetics*
  • Chromosome Mapping
  • Drosophila / embryology
  • Drosophila / genetics*
  • Morphogenesis
  • Mutation*
  • Nervous System / embryology
  • Nucleic Acid Hybridization
  • Plasmids
  • Protein-Tyrosine Kinases / genetics*
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins c-abl
  • Proto-Oncogenes*
  • Transcription, Genetic


  • Cell Adhesion Molecules, Neuronal
  • Proto-Oncogene Proteins
  • fasciclin I
  • Protein-Tyrosine Kinases
  • Proto-Oncogene Proteins c-abl