Exploring the role of Orb in Drosophila oogenesis. N.S Hafer , M.R Wolf , P.D Schedl. Molecular Biology, Princeton University, Princeton, NJ.

   Orb is a Drosophila RNA binding protein that contains two RRM domains. Studies have shown that this protein is expressed in the germline and is involved in the formation of the egg chamber and the determination of the dorsal/ventral (D/V) and anterior/posterior (A/P) axes. Orb performs these functions by translationally regulating the expression of several proteins known to have roles in axis specification. To determine the role of Orb more precisely and identify other regulatory components, a genetic screen was performed to find genes that suppress or enhance D/V defects caused by a dominant negative orb transgene. One interacting line, p622, contains a mutation for the Drosophila Atypical Protein Kinase C (aPKC) protein. aPKC has been shown to form a complex with two proteins, Baz and Par6. This complex is conserved across species and is involved in the generation of cell asymmetry in both the early C. elegans embryo and the Drosophila neuroblast. Other interacting lines encode proteins that interact with microtubules and regulate aspects of oocyte polarity. Studies are underway to further characterize the interaction between Orb and these proteins. Additionally, we are trying to determine if proteins known to interact with aPKC in other model systems play a role in the development of the Drosophila germline.