Figure 4
Generation of mutation-accumulation lines and experimental flies. (A) Mutation-accumulation protocol. A single male bearing an IV-derived X chromosome was mated to multiple DX (C(1)DX y f)-bearing females. A single son, bearing new mutations (white stars), was randomly selected to found the next MA generation. Each generation, triplicate crosses were performed to guard against line loss. (B) Maintenance of control lines. Control lines were initially founded from the same X chromosomes used to create the MA lines. Each generation, males from two vials were mixed together and then split into two vials, each containing 8-10 males and 16-20 DX bearing females. (C) Generation of experimental MA flies. The autosomes from the C and MA males were substituted with a set of marked translocated autosomes ((T(2 : 3)rdgc st in ri pp bw) (grey bars) and crossed to DX-IV females. The resulting males were subsequently crossed to both DX-IV females and FM (FM7a)-IV females to yield males fixed for the MA-X chromosome and females with a balanced MA-X chromosome. Females carrying a balanced C or MA X chromosome in the IV autosomal background were crossed to either random IV males to generate heterozygous females or were crossed to males bearing MA X-chromosomes to generate homozygous females. Males bearing MA chromosomes were collected from both crosses. The sequence of crosses to generate control experimental flies was identical.