The molecular organization of the Star/asteroid region, a region necessary for proper eye development in Drosophila melanogaster.

The Star/asteroid (S/ast) region of Drosophila melanogaster has been cloned by P element transposon tagging using the snw chromosome as a source of defective P elements. In each mutation examined, the element integrated into the region was a 0.5-kb element from a region proximal to sn and not one of the head-to-head elements from the sn locus. Previously described spontaneous and X-ray induced mutations of S and ast were located on the molecular map by Southern analysis and restriction endonuclease mapping of genomic clones. S mutations are either large deletions of the cloned region or DNA breaks located near the P element insertions that cause ast mutations. Both S and ast mutations reduce the steady-state amounts of a 3.4-kb RNA. The molecular data, together with the phenotypic interactions observed for S and ast alleles, are consistent with the interpretation that S and ast mutations are lesions within the same gene or within genes that are functionally related.