The Pax2 homolog sparkling is required for development cone and pigment cells in the Drosophila eye

A new Drosophila Pax gene, sparkling (spa), implicated in eye development, was isolated and shown to encode the homolog of the vertebrate Pax2, Pax5, and Pax8 proteins. It is expressed in the embryonic nervous system and in cone, primary pigment, and bristle cells of larval and pupal eye discs. In spa(poI) mutants, a deletion of an enhancer abolishes Spa expression in cone and primary pigment cells and results in a severely disturbed development of non-neuronal ommatidial cells. Spa expression is further required for activation of cat in cone cells and of the Bar locus in primary pigment cells. Sire suggest close functional analogies between Spa and Pare in the development of the insect and vertebrate eye.