FIG. 7.

Analysis of Drosophila Osa mutants. (A) Osa mutant larvae have decreased levels of H2B-Ub. Acid extracts made from the hypomorphic allelic combination osa³⁰⁸/osa^4H (−/−), osa³⁰⁸/+, or osa^4H/+ (+/−) larvae were immunoblotted with an antibody to H2B. Increasing amounts (1× to 4×) of acid extracts from (−/−) or (+/−) larvae were loaded in lanes 1 to 4 and 5 to 8, respectively. The upper and lower panels are from the same gel. The blot was separated for probing because of the difference in signal intensity between H2B-Ub and H2B. (B to E) Third-instar wing imaginal discs oriented with dorsal up and posterior to the right were stained with anti-Nub (green) and anti-Sens (magenta) antibodies. (B) Wild type; (C) osa³⁰⁸/osa^4H; (D) ap-GAL4/+, UAS-cul-2RNAi/+; (E) ap-GAL4/+; osa³⁰⁸, UAS-cul-2RNAi/osa^4H. Reduction of either osa or cul-2 function causes slight abnormalities in Nub expression throughout the wing pouch and Sens expression at the wing margin, but when both are reduced simultaneously, Sens expression is completely absent and the Nub expression domain is distorted.