IDENTIFICATION OF IMMUNE-SYSTEM AND RESPONSE GENES, AND NOVEL MUTATIONS CAUSING MELANOTIC TUMOR-FORMATION IN DROSOPHILA-MELANOGASTER

We are using Drosophila as a model system for analysis of immunity and tumor formation and have conducted two types of screens using enhance r detector strains to find genes related to these processes: genes exp ressed in the immune system (type A; hemocytes, lymph glands and fat b ody) and genes increased in expression by bacterial infection (type B) . For type A, tissue-specific reporter gene activity was determined. F or type B, a variation of enhancer detection was devised in which beta -galactosidase is assayed spectrophotometrically with and without bact erial infection. Because of immune system involvement in melanotic tum or formation, a third type was hypothesized to be found among types A and B: genes that, when mutated, have a melanotic tumor phenotype. Enh ancer detector strains (2800) were screened for type A, 900 for B, and 11 retained for further analysis. Complementation tests, cytological mapping, P-element mobilization, and determination of lethal phase and mutant phenotype have identified six novel genes, Dorothy, wizard, to te, viking; Thor and dappled, and one previously identified gene, Coll agen IV. All are associated with reporter gene expression in at least one immune system tissue. Thor has increased expression upon infection . Mutations of wizard and dapped have a melanotic tumor phenotype.