In this construct, EcollacZ is sandwiched between Tm1 sequences from -1200 bp to +240 bp (relative to start of transcription), and Tm1 3'UTR sequence. EcollacZ expression is driven in a pattern resembling that of endogenous Tm1. Ovaries, nurse cells and subsequently, oocytes, express EcollacZ. Follicle cells, however, do not express EcollacZ. Maternal expression is detected in early embryogenesis. Subsequently, expression is detected in the cephalic and ventral furrows, and the germ band. The anterior and posterior midgut primordia stain fr EcollacZ. At stage 11, staining is detected in a segmentally repeated pattern in the ectoderm. After stage 13, the brain, CNS and midgut constriction stain for EcollacZ.