Abstract
Background
The frizzled pathway in Drosophila has been studied intensively for its role in
the development of planar polarity in wing hairs, thoracic bristles and
ommatidia. Selected cells in the arista (the terminal segment of the antenna)
elaborate a lateral projection that shares characteristics with both hairs and
bristles.
Results
We found that mutations in putative downstream members of the frizzled pathway,
such as inturned resulted in multipled and split laterals, but no obvious
polarity defects. Mutations in upstream genes such as frizzled did not show an
adult arista phenotype. When we examined lateral development in the mutants we
found that, as is the case on the wing for hair development the frizzled pathway
regulated the subcellular location for lateral initiation. However, on the
arista an altered location for lateral initiation did not result in altered
polarity, as did an altered site for hair initiation. The regulation of lateral
development involved the preferential accumulation of Frizzled protein at the
distal edges of lateral cells much as is seen on the wing. In contrast to the
situation in wing cells, in arista cells the location for lateral initiation was
close to but did not overlap the region of preferential Frizzled accumulation.
Conclusion
Our data indicates that a modified version of the frizzled pathway
regulates arista development. We conclude that the lack of a polarity defect in
mutant aristae is likely to be a consequence of inherent differences in the cell
biology of wing hair and lateral forming cells.