ALT Figure 1A-C: Drosophila Set1 is required cell-autonomously for germline maintenance and differentiation. (A) Schematic of the tip of the Drosophila testis. CySC, cyst stem cell; GSC, germline stem cell. (B) nos>Control RNAi (Ctrl KD) and nos>set1 RNAi (Set1 KD) flies were grown at 18°C until eclosion, and then shifted to 25°C for 0, 1, 3, 5 or 7 days. (C) Representative Ctrl KD and Set1 KD testes at the third instar larval stage (L3), day 0, 1, 3, 5 and 7 post-eclosion stained with the GSC lineage marker Vasa (green), Arm (red) or Fas III (red) for the hub area (white dashed outline), 1B1 for the spectrosome and fusome, and Tj (magenta) for the CySC lineage cells. Yellow dotted lines indicate overpopulated early germ cells.