Fig. 5. Localized RNAs and proteins associate with the fusome and Balbiani body. (A) In situ hybridization reveals that osk RNA (green) associates with the central fusome (red) within the future oocyte beginning in region 2 (arrowhead). The RNA moves to the posterior of the oocyte during stage 1 (rightmost follicle). (B) An early region 3 oocyte (broken line) shown at higher magnification, reveals that osk RNA (green) partially overlaps (yellow) the Balbiani body on the posterior side of the mitochondrial mass (red, anti-ATP synthase). The arrowhead indicates the fusome (blue, 1B1). B' is the same image as B without the green channel, in order to better show the Balbiani body (arrow). (C) orb RNA (green), like osk RNA, associates with the center of the fusome (red) beginning early in region 2 (arrowheads), and then moves to the oocyte posterior in stage 1 (rightmost follicle). (D) Like osk RNA, orb RNA (green) also overlaps with the Balbiani body (red). D' is the same as D without the green channel, in order to better show the Balbiani body (arrow). (E,F,H) Cup protein (red) associates with the center of the fusome (blue) and with mitochondria (green) in region 2 cysts. (G,I) Orb protein (red) localizes to a similar position as Cup (green, mitochondria). (H,I) Both Cup (red, H) and Orb (red, I) briefly associate with the edge of the Balbiani body mitochondria (green) in early region 3 oocytes and then move to the oocyte posterior (not shown). Scale bars: in G, 10 µm for A,C,E-G; in D' 1 µm for B,B',D,D'; in I, 1 µm for H,I.