EPITHELIAL HYPERPLASIA OF IMAGINAL DISCS INDUCED BY MUTATIONS IN DROSOPHILA TUMOR-SUPPRESSOR GENES - GROWTH AND PATTERN-FORMATION IN GENETIC MOSAICS

Lethal mutations in the giant discs (Igd) and fat (ft) tumor suppressor genes of Drosophila cause epithelial hyperplasia in all imaginal discs. By contrast, mutations in the vestigial (vg) gene adversely affect cell viability in the wing imaginal discs and consequently cause loss of pattern in the adult wings. However, combining homozygous Igd or ft mutations with homozygous vg(1) increases the size of the wing imaginal discs and partially restores the bristle pattern in the wings of pharate adults. Comparable pattern restoration in vg(1) wings is also induced by a newly isolated weak hypomorphic Igd(3) allele. Further, mosaic analysis revealed that whereas Igd clones generated by the Minute technique display abnormal differentiation, those induced in a homozygous vg(1) background exhibit autonomous restoration of wing pattern. These results suggest that pattern restoration in vg(1) wings can serve as an assay for hyperplasia induced by mutations in Drosophila tumor suppressor genes. (C) 1995 Academic Press, Inc.