The only function of grauzone required for Drosophila oocyte meiosis is transcriptional activation of the cortex gene

The grauzone and cortex genes are required for the completion of meiosis in Drosophila oocytes. The grauzone gene encodes a C2H2-type zinc-finger tran scription factor that binds to the cortex promoter and is necessary for hig h-level activation of cortex transcription. Here we define the region of th e cortex promoter to which Grauzone binds and show that the binding occurs through the C-terminal, zinc-finger-rich region of the protein. Mutations i n two out of the five grauzone alleles result in single amino acid changes within different zinc-finger motifs. Both of these mutations result in the inability of Grauzone to bind DNA effectively. To determine the mechanism b y which Grauzone regulates meiosis, transgenic flies were produced with an extra copy of the cortex gene in homozygous grauzone females. This transgen e rescued rho meiosis arrest of embryos from these mutants and allowed thei r complete development, indicating that activation of cortex transcription is the primary role of Grauzone during Drosophila oogenesis. These experime nts further define a new transcriptional pathway that controls the meiotic cell cycle in Drosophila oocytes.