ARAUCAN AND CAUPOLICAN, 2 MEMBERS OF THE NOVEL IROQUOIS COMPLEX, ENCODE HOMEOPROTEINS THAT CONTROL PRONEURAL AND VEIN-FORMING GENES

In Drosophila imaginal wing discs, the achaete-scute (ac-sc) proneural genes and rhomboid (veinlet) are expressed in highly resolved pattern s that prefigure the positions of sensory organs and wing veins, respe ctively. It is thought that these patterns are generated by a combinat ion of factors (a prepattern) regulating these genes. We provide evide nce for the existence of this prepattern by identifying two of its fac tors, Araucan and Caupolican. They are members of a novel family of ho meoproteins, with homologs in vertebrates. Araucan and Caupolican, pre sent in domains of the imaginal discs larger than those expressing as- sc and rhomboid, are necessary for expression of these genes in the ov erlapping domains. Araucan and Caupolican appear to be positive, direc t regulators of ac-sc.