Fig. 2: Acc-mediated balance between FAS and FAO regulates oogenesis, with FAO playing distinct roles in fusome branching and oocyte determination.

A Germaria with LamC (red, cap cell nuclear envelopes), 1B1 (red, fusomes), and BODIPY (green, neutral lipid droplets). Yellow lines indicate GSCs, and the yellow dashed circle outlines cysts with unbranched fusomes. B Number (no) of lipid droplets (LDs) per GSC. Each dot represents a GSC. C GSC number in the germaria in the indicated genotypes. The left y axis shows the proportion of germaria carrying the indicated GSC number. The right y axis shows the average GSC number per germarium (D) Percentage of germ cell cysts carrying at least 4 germ cells with unbranched or single-branched fusomes. E Ovarioles with α-spectrin (red, fusomes, and follicle cell membranes) and Orb (green, an oocyte marker). Yellow asterisks indicate posteriorly located oocyte in the egg chamber, denoted as normal localization. Percentages represent the proportion of egg chambers with normal oocyte localization; parentheses show egg chamber numbers. F Ovaries carrying mature eggs (white and big eggs, asterisks), denoted as normal. Percentages represent the proportion of normal ovaries; the number of ovaries imaged and analyzed is shown in parentheses. G Number of eggs produced per female of the indicated genotype on the fourth day after mating. N = 4 biological replicates were performed. Orange-filled and unfilled circles on the x axis in (B, D, and G) represent the expression dCPT1^RNAi and gfp^RNAi, respectively. Error bars indicate mean ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001. Asterisks indicate significant differences compared with control (gfp^RNAi & mCherry^RNAi), or comparisons between two groups indicated by a line. Statistical analysis in B, C, and G were performed using the unpaired two-tailed Student’s t-test, and in (D) using the two-tailed chi-squared test. The numbers above each bar in C or beside each bar in D represent the number of germaria or germ cell cysts analyzed, respectively. UAS-RNAi expression was driven by nos-GAL4; D7, 7-day-old. Scale bars: 10 μm in A, 20 μm in E, and 1 mm in F.