lacZ gene expression is driven by a chimeric D. melanogaster and D. grimshawi Cp18 regulatory region, with D. melanogaster Cp18 promoter deleted for base pairs +7 to -931 and D. grimshawi Cp18 5' sequences from -5 to -442 base pairs inserted.
Moderate levels of staining were observed which were most evident during oogenesis stages S13 and S14.