The recovery and preliminary characterization of X chromosome mutants affecting imaginal discs of Drosophila melanogaster

Abstract

A selection method especially designed for isolation of X-linked lethals in Drosophila having defective imaginal discs has generated 26 mutants with high larval viability, but which terminate development in late larval and prepupal stages. The mutants are tentatively classified into four categories, according to the morphological appearance of their imaginal discs in third-instar larvae, and are further characterized with reference to autonomy/nonautonomy and to capacity for in vitro evagination of discs. The four categories are as follows: 1. discs degenerate = extreme reduction of disc tissue (8 mutants). Of 7 mutants tested, all appear to be autonomous. 2. discs small = reduction in size of disc tissue (7 mutants). Of 6 mutants tested, 5 are nonautonomous. However, discs from 4 of the nonautonomous mutants fail to evaginate in vitro . 3. discs large = hypertrophy of disc tissue (1 mutant). The mutant is phenotypically similar to an allele of lethal giant larvae (l(2)gl 4 ) . 4. discs normal = normal appearance of disc tissue (10 mutants). Of 9 mutants tested, 5 are nonautonomous. Discs from one mutant evaginate abnormally in vitro and in vivo .