Lipid signaling between soma and germline is required for Drosophila spermatogenesis. Geulah Ben-David, Josefa Steinhauer. Department of Biology, Yeshiva College, New York, NY.

   Lysophospholipids are single fatty acid chain phospholipids that can promote proliferation, motility, and survival when added to the media of cultured cells. In mammals, lysophospholipid signaling has been linked to cancer progression and has been implicated in normal physiology and development. Mechanisms that regulate lysophospholipid levels in vivo are not well understood. One pathway by which lysophospholipids are generated is the Lands cycle, which converts membrane phospholipids to lysophospolipids by removal of a fatty acid chain (deacylation) via the activity of phospholipase A₂ (PLA₂). PLA₂ activity is counterbalanced by the activity of membrane-bound O-acyltransferase (MBOAT) family enzymes, which catalyze the reacylation of lysophospholipids into phospholipids. Oysgedart (Oys) and Nessy (Nes) are Drosophila MBOAT family lysophospholipid acyltransferases (LPLATs). Adult male oys nes mutants are sterile with a complete block in spermatid individualization. Here we show that oys and nes RNAs are expressed in the testis, as are four of the nine Drosophila PLA₂ genes. We are testing whether these PLA₂s are required for spermatogenesis using RNAi. The spermatogenesis defect of oys nes mutants can be rescued by expression of Oys cDNA in the somatic cyst cells, but not the germline. In oys nes mutants, molecular markers of cyst cell development are expressed normally, and cyst cell membranes also appear normal with a fluorescent membrane marker. Additionally, oys nes mutant embryos display defects in germ cell migration, a process that relies on lipid signaling, and oys and nes are required in the soma for this process. Together, our data suggest that Oys and Nes mediate cell communication between soma and germline in two stages of development, by regulating the availability of lysophospholipid signals. These studies may provide a foundation for investigating the roles of lysophospholipid signals in cell communication and fertility.