(A) Schematic of NTR-mCherry fusion protein generated by Gal4-VP16 transactivation of UAS:nfsB-mCherry transgene. Transgenic c223 larvae at 80 hpf (B–G) and c230 larvae at 54 hpf (H-M) were treated with Met from 56 to 80 hpf (B, C, D) and 30 to 54 hpf (H, I, J), respectively. Negative, age-matched controls had either one (E, F, K, L) or no copies (D, G, J) of the UAS:nfsB-mCherry. Transactivation of the NTR-mCherry fusion protein in c223 in Z-stack projections of the trunk neural tube superimposed over bright field images (B and E) or in transverse vibratome sections of the neural tube (C and F), and in the c230 (H, K) notochord (asterisks). Larvae expressing NTR-mCherry show a prodrug dependent loss of fluorescent cells in the developing CNS (B, C) and notochord (H, I corresponding DIC image) when compared to untreated controls (E, F and K, L corresponding DIC image, respectively). In B to G, nuclei are counterstained with Hoechst dye. Inset panels show high magnification of the nuclei in cells of the ventral neural tube overlaying the notochord (asterisks)
Arrows and arrowheads (C, D and F, G) mark individual fluorescent floor plate cells corresponding to identical cells in high magnification inserts. Following prodrug treatment, the few remaining NTR-mCherry expressing floor plate cells possess fragmented nuclei indicative of being apoptotic (inset in F). (M) Morphology of c230 larvae at 54 hpf either treated with Met (upper, as in H,I) or untreated (middle as in J, or lower as in K,L) demonstrating that ablating notochord cells leads to reduced body length.