P-ELEMENT MUTATIONS AFFECTING EMBRYONIC PERIPHERAL NERVOUS-SYSTEM DEVELOPMENT IN DROSOPHILA-MELANOGASTER

The Drosophila embryonic peripheral nervous system (PNS) is an excelle nt model system to study the molecular mechanisms governing neural dev elopment. To identify genes controlling PNS development, we screened 2 000 lethal P-element insertion strains. The PNS of mutant embryos was examined using the neural specific marker MAb 22C10, and 92 mutant str ains were retained for further analysis. Genetic and cytological analy sis of these strains shows that 42 mutations affect previously isolate d genes that are known to be required for PNS development: longitudina ls lacking (19), mastermind (15), numb (4), big brain (2), and spitz ( 2). The remaining 50 mutations were classified into 29 complementation groups and the P-element insertions were cytologically mapped. The mu tants were classified in five major classes on the basis of their phen otype: gain of neurons, loss of neurons, organizational defects, pathf inding defects and morphological defects. Herein we report the prelimi nary phenotypic characterization of each of these complementation grou ps as well as the embryonic lacZ expression pattern of each P-element strain. Our analysis indicates that in most of the P-element insertion strains, the lacZ reporter gene is not expressed in the developing PN S.