Figure 2.—

A genetic screen for pupal lethal mutations. Males fed 10 mM EMS were mated en masse to females carrying a salivary gland-specific GFP marker on the X chromosome (fkh>GFP = w¹¹¹⁸, {fkh-GAL4}, {UAS-GFP}) and dominant markers Pr Dr along with a Tubby-marked balancer (TM6B, HuTb) on the third chromosome. Individual F₁ males were crossed to the same female stock used in the F₀ generation, allowing the establishment of F₂ stocks, each of which carries a unique mutagenized third chromosome. We established 19,059 F₂ stocks from 26,481 F₁ crosses and identified 8636 lethal mutations in the F₃ generation. Of these, 566 had a primary lethal phase during pupal stages of development.