Fig. 4. Decreased chorion gene amplification and thin eggshells caused by loss of E2f2. (A) Photomicrograph of a yw⁶⁷ wild-type egg from the dorsal perspective. All other panels show anterior towards the left and dorsal towards top. (B-D) Eggs laid by a Df(2L)E2f2³²⁹/Df(2L)E2f2³²⁹ mutant females. Note that the chorions are more translucent compared with wild type. (E) Egg laid by a Df(2L)E2f2³²⁹/Df(2L)E2f2³²⁹; P[E2f2⁺; Mpp6⁺] female. (F) Southern hybridization was used to measure chorion gene amplification in stage 13 egg chambers dissected from yw⁶⁷ wild type (lanes 1, 2, 3) and Df(2L)E2f2³²⁹/Df(2L)E2f2³²⁹; P[E2f2^–; Mpp6⁺]/+ (lanes 4, 5, 6) females. Genomic DNA (1 µg, lanes 1 and 4; 2.5 µg, lanes 2 and 5; 5 µg, lanes 3 and 6) was simultaneously hybridized with a rosy gene probe and a third chromosome chorion gene cluster probe. The intensity of the 7.8 kb rosy fragment and the 3.8 kb chorion fragment were compared for each lane using a PhosphoImager. A 50% decrease in chorion gene amplification is reproducibly observed in E2f2 mutants.