Mutations in the Drosophila gene prickle alter tissue polarity by disrupting a local frizzled-dependent signal. J. Taylor , J. Charlton , R. Krasnow , P.N. Adler. Department of Biology, University of Virginia, Charlottesville, VA.

   The tissue polarity genes of the frizzled signaling/signal transduction pathway control wing hair polarity by regulating the subcellular location for the initiation of the prehair. The formation of the prehair in the vicinity of the distal vertex leads to distally pointing adult hairs. Mutations that inactivate the frizzled signaling/ signal transduction pathway result in abnormal polarity patterns of the adult hairs. The mutant pattern is not random, but stereotypical for each mutant. The pattern is quite similar for mutations in different frizzled pathway genes. Mutations in the prickle gene produce an abnormal polarity pattern distinct from those of the frizzled pathway genes. However, the function of the frizzled pathway is required for the production of this pattern. We used the domineering nonautonomy of frizzled and Van Gogh clones to assess the direction of frizzled signaling in prickle wings. We found that the anatomical direction of tissue polarity signaling is altered in prickle mutants in a way that predicts the mutant polarity pattern of prickle wings. Further we found cells in clones mutant for prickle had altered polarity. Notably, this polarity was the same as predicted by the pattern generated in homozygous prickle mutant flies. Our data argue that mutations to prickle are disrupting a polarity signal that acts locally, rather than over the length of the wing.