Using lacZ-specific antibodies to western blots of embryos, the Sry-deltaFBtr0091350:pb-XRlacZ fusion protein is detected throughout embryogenesis.The lacZ activity of the Sry-deltaFBtr0091350:pb-XRlacZ fusion protein is detected in the nuclei of many adult somatic and germ line tissues. The oocyte provides the only instance of cytoplasmic localization. Activity is also present in first to third instar larvae, with strong nuclear expression in salivary glands and imaginal discs.