CHARACTERIZATION OF INSERTION MUTATIONS L EADING TO MITOSIS ABNORMALITIES IN DROSOPHILA-MELANOGASTER BY MEANS OF THE REPORTER GENE-CONTAINING TRANSPOSON

Transpositions of the vector P[IArB] into the regions 78D, 61F, and 85 F of chromosome 3, which result in various anomalies of mitoses in neu ral ganglions of homozygous larvae, were obtained by insertion mutagen esis. The tissue specificity of regulatory elements controlling the re porter gene was studied by staining for the activity of beta-galactosi dase reporter gene of the vector P[IArB]. These regulatory elements ar e suggested to be the enhancers of the genes carrying insertions. In a ll studied mutants, staining for beta-galactosidase was found in tissu es containing actively proliferating cells. The staining of germarium in adult female ovaries was the most pronounced. The germarium stainin g pattern was used for the identification of novel insertions leading to mitosis abnormalities. The P1003 (99F) insertion was found, which a ccording to preliminary data leads to an increase in the mitotic index and anomalies of chromosome structure in neuroblasts of homozygous la rvae. In addition, the 22w (42A) insertion leading to chromosome arres t in metaphase was found.