Fig. 4. Vas-eIF5B interaction is required for the progression of oogenesis. (A) Western blot of ovarian extracts from wild-type (OreR), vas^PH165, vas^PH165;P{vas⁺} and vas^PH165;P{vas⁶¹⁷} females was probed with anti-Vas. The same blot was probed with anti-4E-BP as a loading control. (B) Ovaries from vas ^PH165 females produce few mature stage 14 eggs owing to a developmental arrest during oogenesis. (C) Expression of a wild-type vas⁺ transgene rescues this defect of the vas^PH165 mutation, allowing the production of abundant stage14 eggs. (D) Ovaries from vas^PH165;P{vas⁶¹⁷} females resemble those of vas^PH165, exhibiting a similar developmental arrest during oogenesis and producing few mature eggs.