Developmental expression of blt mRNA. The RT-PCR assay was performed with the total RNA extracted at different developmental stages. Shown are results from a typical experiment. Lane 1: embryos, 0–6 h after egg laying (AEL); lane 2: late embryos (17–18 h AEL) and 1st instar larvae; lane 3: 2nd-3rd instar larvae; lane 4: pupae; lane 5: adult heads; lane 6: adult female body; lane 7: adult male body. Upper bands, blt mRNA; lower bands, ribosomal rp46 mRNA (control). Note the absence of blt mRNA in lane 1, the early embryos.