A TEMPERATURE-SENSITIVE BRAIN-TUMOR SUPPRESSOR MUTATION OF DROSOPHILA-MELANOGASTER - DEVELOPMENTAL STUDIES AND MOLECULAR LOCALIZATION OF THE GENE

The recessive-lethal, temperature-sensitive (ts) mutation of the tumor suppressor gene lethal(3)malignant brain tumor (l(3)mbt) causes in a single step the malignant transformation of the adult optic neuroblast s and ganglion mother cells in the larval brain at the restrictive tem perature of 29-degrees-C. The transformed cells are differentiation-in competent and grow autonomously in a lethal and invasive fashion in si tu in the brain as well as after transplantation in vivo into wild-typ e adult hosts. The imaginal discs show epithelial overgrowth. At the p ermissive temperature of 22-degrees-C development is completely normal . The ts-period of gene activity responsible for 100% brain tumor supp ression and normal imaginal disc development encompasses the first six hours of embryonic development. The l(3)mbt gene function is, however , also required thereafter for the proper differentiation of the brain and the imaginal discs. The l(3)mbt gene is located cytologically in the salivary gland chromosome bands 97E8-F11, and in molecular terms i n 29 kb of DNA detected via a P-element insertional deletion.