Paul Adler

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  Planar polarity of cuticular hairs and cuticle hydrophobicity
  Paul Adler

  The cuticular exoskeleton of insects such as Drospophila is decorated with a variety of structures. Some of these are sensory (e.g. sensory bristles) while others are not innervated (e.g. cuticular hairs or trichomes). Much of the cuticular surface is covered by hairs and in any body region these display a consistent planar polarity. This has best been studied on the wing where each epithelial cell produces a single distally pointing hair. The initial development of each hair is formed by a cytoskeletal mediated outgrowth that forms at the distal edge of each cell. The proteins of the fz/stan pathway that regulates this all accumulate asymmetrically in wing cells prior to hair outgrowth. A number of models have been suggested to explain how this pathway restricts the activation of the actin cytoskeleton to the distalmost part of the cell. These and the evidence for multiple factors influencing the activation of the cytoskeleton will be discussed.

  
  

  The cuticle of many insects is highly hydrophobic. For example, when a Drosophila wing is dropped into water is not only floats it does not wet. Two factors, surface structures (e.g. hairs) and the waxy coating of the cuticle have been suggested to be important for hydrophobicity. We have found that the wing does not become hydrophobic until shortly before the adult ecloses well after hair morphogenesis and the basis for the lipid coating of the cuticle will be discussed.