Plasma membrane polarity and compartmentalization are established before cellularization in the fly embryo

Dev Cell. 2009 Jan;16(1):93-104. doi: 10.1016/j.devcel.2008.11.003.


Patterning in the Drosophila embryo requires local activation and dynamics of proteins in the plasma membrane (PM). We used in vivo fluorescence imaging to characterize the organization and diffusional properties of the PM in the early embryonic syncytium. Before cellularization, the PM is polarized into discrete domains having epithelial-like characteristics. One domain resides above individual nuclei and has apical-like characteristics, while the other domain is lateral to nuclei and contains markers associated with basolateral membranes and junctions. Pulse-chase photoconversion experiments show that molecules can diffuse within each domain but do not exchange between PM regions above adjacent nuclei. Drug-induced F-actin depolymerization disrupted both the apicobasal-like polarity and the diffusion barriers within the syncytial PM. These events correlated with perturbations in the spatial pattern of dorsoventral Toll signaling. We propose that epithelial-like properties and an intact F-actin network compartmentalize the PM and shape morphogen gradients in the syncytial embryo.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Actins / metabolism
  • Animals
  • Bridged Bicyclo Compounds, Heterocyclic / metabolism
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Cell Nucleus / metabolism
  • Cell Polarity / physiology*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / anatomy & histology
  • Drosophila melanogaster / embryology*
  • Drosophila melanogaster / metabolism*
  • Fluorescence Recovery After Photobleaching
  • GAP-43 Protein / metabolism
  • Giant Cells / cytology
  • Giant Cells / metabolism
  • Mitosis / physiology
  • Thiazolidines / metabolism


  • Actins
  • Bridged Bicyclo Compounds, Heterocyclic
  • Drosophila Proteins
  • GAP-43 Protein
  • Thiazolidines
  • latrunculin A