Figure 1

Fly genetics. (a) The fly strain used in this study is isogenic to a yw standard lab strain, but carries neutral white⁺ transgene insertions on the two major autosomes. The P-element insertion on chromosome 2 localizes to the promoter of CG31666 and the other transposon is situated 5' to CG32111 on chromosome 3. The white⁺ expression domains are restricted to the anterior and dorsal parts of the eye in the respective strains, and the patterns overlap such that the genotypes can be unambiguously assessed from eye appearance. (b) The genetic scheme ensures that mutagenized F0 chromosomes are passed unrecombined, because they are transmitted via males only, and that flies carrying a mutation can easily be singled out on the basis of the eye phenotype. The mutagenized flies are always crossed back to the parental wild type, and only chromosomes from F2 progeny carrying a confirmed mutation are balanced.