Regulation of Gonad Morphogenesis in Drosophila Melanogaster by Broad Complex, Tramtrack and Bric à Brac Transcription Factors

During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of SGPs and PGCs to form a gonad with the proper architecture not only affects germ cell development, but also can result in infertility. We have characterized the phenotypes of two genes, longitudinals lacking (lola) and ribbon (rib), required for the coalescence and compaction of the embryonic gonad in Drosophila melanogaster. Both rib and lola are expressed in the SGPs and to a lesser extent in the PGCs of the developing gonad, and genetic interaction analysis suggests these proteins cooperate to regulate gonad development. Analysis of colocalization with marks of transcriptional activation and repression on polytene chromsomes reveals that Rib and Lola colocalize with both marks. Thus, these studies demonstrate that Rib and Lola function cooperatively to regulate transcription of target genes and thereby promote embryonic gonad morphogenesis.