Figure 1.

Collagen IV produced in adult adipocytes is required for GSC maintenance. (A) The Drosophila ovary is composed of 16–20 ovarioles that contain progressively older follicles. Each follicle consists of a germline cyst (one oocyte and 15 nurse cells) surrounded by somatic follicle cells (blue), and they are produced in the germarium at the anterior tip of each ovariole. (B) Each germarium contains two–three GSCs that reside in a somatic niche composed primarily of cap cells. GSCs divide asymmetrically to self-renew and generate a cystoblast that forms a 16-cell cyst. GSCs and germline cysts are identified based on the morphology and position of the fusome, a germline-specific organelle (de Cuevas and Spradling 1998). Follicle cells envelop the germline cyst to form a follicle. (C) The adult fat body (composed of adipocytes and hepatocyte-like oenocytes) surrounds the ovary. (D) Germaria at 14 days of adult adipocyte-specific Luc RNAi control or vkg RNAi. Vasa (red), germ cells; α-Spectrin (green), fusome; LamC (green), cap cell nuclear lamina; DAPI (blue), nuclei. GSCs are outlined. Bar, 10 µm. (E–G) Average number of GSCs per germarium over time of control, Cg25C RNAi (E), vkg RNAi (F), or SPARC RNAi (G) (mean ± SEM, * P < 0.05 and **** P < 0.0001, two-way ANOVA with interaction). See also Figures S1 and S2. GSC, germline stem cell; RNAi, RNA interference; st., stage.