Completion of meiosis in Drosophila oocytes requires transcriptional control by Grauzone, a new zinc finger protein

Mutations in grauzone or cortex cause abnormal arrest in Drosophila female meiosis, We cloned grauzone and identified it as a C2H2-type zinc finger tr anscription factor. The grauzone transcript is present in ovaries and at la ter developmental stages. A Grauzone-GFP fusion protein is functional and l ocalizes to nuclei of both nurse cells and follicle cells during oogenesis. Three lines of evidence indicate that grauzone and cortex interact: reduci ng cortex function enhanced the grauzone mutant phenotype; cortex transcrip t abundance is reduced in the absence of grauzone function and Grauzone pro tein binds to the cortex promoter. These results demonstrate that activatio n of cortex transcription by grauzone is necessary for the completion of me iosis in Drosophila oocytes, and establish a new path way that specifically regulates the female meiotic cell cycle.