Requirements for scribble expression in newly formed gonads of Drosophila embryos.

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila, and encodes two protein isoforms. Here, we report the pattern of Scrib1 synthesis in pole cells and embryonic gonads. We found that Scrib1 synthesis became strongly enhanced in pole cells at the time of gonad formation and was also detectable in cortical domains of gonadal mesodermal cells adjacent to pole cells. Scrib1 synthesis in mesodermal cells was independent of pole cells and occurred in agametic valois and capsuléen embryonic gonads. In contrast, Scrib1 synthesis in pole cells required contact with gonadal mesodermal cells as revealed by the absence of Scrib1 in wunen or tinman-zinc finger homeodomain-1 pseudo-gonads made only of aggregated pole cells.