Fig. 5. yps^JM2 rescues orb-associated defects in osk protein expression, but does not alter the expression or localization of Orb protein. The ovaries in A-D were labeled with an antibody to the Osk protein. Arrows in A-D indicate the posterior poles of stage-10 oocytes. (A) w¹¹¹⁸ (control) egg chambers. Osk protein is present at the posterior pole of the stage-10 oocyte. (B) An identical pattern is observed in yps^JM2/yps^JM2 egg chambers. (C) In orb^mel/orb^F303 mutant egg chambers, Osk protein is not detected at the posterior pole of the oocyte. (D) In many yps^JM2orb^mel/yps^JM2orb^F303 doubly mutant egg chambers, Osk protein is present, localized at the posterior pole. The ovaries shown in A-D were also labeled with an antibody to the Orb protein (E-H). (E) In control egg chambers, Orb concentrates in the oocyte from early oogenesis, and is present at lower levels in the nurse cells. During mid-oogenesis the protein accumulates at the anterior and posterior (arrow) poles of the oocyte. (F) An identical pattern is observed in yps^JM2/yps^JM2 egg chambers. (G) In orb^mel/orb^F303 egg chambers, Orb accumulates in the nurse cells to a higher level than in wild type. During mid-oogenesis, Orb is particularly concentrated in the nurse cells that border the oocyte (arrow). Orb rarely accumulates at the anterior or posterior poles of the oocyte. (H) In yps^JM2orb^mel/yps^JM2orb^F303 ovaries, the distribution of Orb is identical to orb^mel/orb^F303 ovaries.