Identification of somatic factors controlling ovarian development by RNAi screening. Chun-Ming Lai^1,2, Yueh Cho¹, Hwei-Jan Hsu¹. 1) Inst Cellular & Organismic Biol, Academia Sinica, Taipei, Taipei, Taiwan; 2) Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan.

   Germ cells are the only cell type that transmits genetic information to the next generation. Germ cell development and germline stem cell (GSC) specification require interaction with their somas. The molecular mechanisms underlying these processes, however, are largely unknown. The Drosophila ovary is an excellent model in which to study germ cell-soma interactions, as it produces eggs daily, houses well-characterized GSCs, and is easily manipulated. To identify factors in the soma that affect germ cells, we conducted a small-scale RNAi targeting screen. We first selected 560 UAS-RNAi lines with targets involved in the control of female fertility from the NIG-Fly stock center. We individually overexpressed these RNAi lines in the soma during ovarian development using a bab1-GAL4 driver, and examined egg production and ovary morphology at the adult stage. We identified 42 candidate genes that potentially function in the soma and contribute to ovarian development. Among these genes, Transformer, Sex lethal and Traffic jam have been reported to control soma specification and function, validating our approach. Eight of our candidate genes encode proteins belonging to the Notch, Bmp, Hh, Wnt and Ras signaling pathways, indicating that these pathways are critical for appropriate soma development. Other candidate genes encode proteins that regulate cell cycle progression, cell movement, chromatin remodeling, cytoskeleton arrangement, and transcriptional regulation. We are currently investigating how these genes regulate soma-germ cell interactions during ovarian development.