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Abstract

The process of cell migration is essential for the development and functioning of most multicellular organisms. Studying germ cell migration in Drosophila embryos gives us a convenient system to understand the dynamics of this process. Usually migration of cells is mediated or controlled by a number of attractive and/or repulsive cues present in their environment. In Drosophila, a number of such cues have been identified as being important for the correct migration of the germ cells from the posterior of the embryo at early development to their final destination in the embryonic gonads. Wunen and Wunen2 provide repulsive cues that cause the germ cells to avoid areas in the soma where they are expressed. Both genes encode lipid phosphate phosphatases and act redundantly. In addition to their role in somatic cells, wun and wun2 are maternally provided and required in germ cells for their survival: In embryos with no maternal wun and wun2, germ cells form normally but all of them die during migration through the midgut. Although in vitro these enzymes can dephosphorylate a number of lipid phosphates such as lysophosphatidic acid and sphingosine-1phosphate, their in vivo substrate is not yet known. To help find the in vivo substrate and also other interactors of wunens, we are performing an enhancer/suppressor screen. We are using the sensitized background of maternal wun2 null embryos, where only half of the number of germ cells survive, and are screening for deficiencies that can suppress or enhance this phenotype. Through this we hope to find genes involved in not only the synthesis of the in vivo substrate but also its modification and transport.