Fig. 7

Expression of wnt1 and dlA in Delta-Notch mutants. All images show dorsal views with anterior to the top. A-D: wnt1 expression in dlA^dx2 mutants at 16 hours postfertilization (hpf, A), 18 hpf (B), 20 hpf (C), and 27 hpf (D). E: dlA expression in a severely affected dlA^dx2 mutant at 30 hpf. F-I: wnt1 expression in mib^ta52b mutants at 16 hpf (F), 18 hpf (G), 20 hpf (H), and 27 hpf (I). J: Expression of dlA in a mib^ta52b mutant at 30 hpf. K-N: dlA expression at 30 hpf in mib^ta52b mutants injected with pHS-wnt1-myc and subjected to serial heat shocks beginning at 16 hpf (K), no heat shock (L), a single heat shock delivered at 24 hpf (M), or serial heat shocks beginning at 24 hpf (N). O: expression of dlA at 30 hpf in a mib^ta52b mutant injected with pHS-GFP and given serial heat shocks beginning at 16 hpf. P: dlA expression in a wild-type embryo injected with pHS-wnt1-myc and given serial heat shocks beginning at 16 hpf. Q: wnt1 staining in a wild-type embryo injected with pHS-wnt1-myc and given serial heat shocks beginning at 16 hpf. R-T: wnt1 staining in mib^ta52b mutants injected with pHS-wnt1-myc and given serial heat shocks beginning at 16 hpf. Arrowheads indicate stripes of wnt1 expression at presumptive rhombomere boundaries. Note the close proximity of darkly stained plasmid-containing cells in or near each stripe of endogenous wnt1 (R,S), compared with the absence of endogenous wnt1 stripes when pHS-wnt1-myc is absent (T). Red arrows show groups of cells containing pHS-wnt1-myc in the center of rhombomere 3. This rhombomere is particularly easy to locate and assess, because it is abnormally large at this stage in mib^ta52b mutants, and its position relative to the anterior edge of the otic vesicle is highly reproducible. Note the absence of stripes of endogenous wnt1 expression in r-center cells surrounding plasmid-containing cells. Scale bar in T = 45 μm in S, 90 μm in A-R,T.