traffic jam, a gene required for gonad morphogenesis encodes a Drosophila Maf transcription factor (DMaf). M.A. Li ¹, R. Avancini ², F. Laski ³, D. Godt ¹. 1) Department of Zoology, University of Toronto, Toronto, Ontario, Canada; 2) Department of Parasitology, UNICAMP, Campinas, Brazil; 3) Molecular Biology Institute, University of California at Los Angeles, Los Angeles, USA.

   Differentiation of germ cells into eggs and sperms depends on multiple interactions with somatic cells. Here, we describe the characterization of the gene traffic jam (tj) that is required for both gonad morphogenesis and gametogenesis. tj mutant flies are sterile, their gonads rudimentary. We find that tj encodes a nuclear protein that belongs to the evolutionary conserved family of large Maf (musculo-aponeurotic fibrosarcoma) factors, a subfamily of basic-leucine zipper transcription factors, other members of which are the v-maf oncogene and the vertebrate mafB/kreisler gene. Throughout development we find tj expressed in the gonads, and here specifically in those somatic cells that contact the germ cells. In tj mutants the contact between the somatic cells and the germline cells is disrupted. The interstitial cells that normally intermingle the female primordial germ cells, and the cyst cells that normally ensheath the male germ cells form cell populations separated from the germ cells. These data suggest that the severe disruption of gonad morphogenesis in tj mutants is caused by defects in the interactions between different cell populations.