Gsc promotes EMT of otic neuroblasts. (A–F) Expression of ngn1 in cross-sections passing through the widest part of the neurogenic domain (dorsal up, medial left) just posterior to the utricular sensory epithelium expression in controls, gsc mutants, and hs:gsc embryos at 24 hpf (A–C) or 43.5 hpf (D–F). Control and transgenic embryos were heat shocked at 22 hpf (A and C) or 42 hpf (D and F). The otic epithelium is outlined in each image. (G) Mean and SD of the total number of ngn1+ cells in the otic epithelium and outside the otic vesicle for the genotypes indicated in the color key (counted from the serial sections, n = 3 or 4 otic vesicles per time point). The number of ngn1+ neuroblasts in the otic epithelium was normal in gsc mutants and morphants at all stages, except for a small but significant reduction seen in gsc morphants at 24 hpf (P < 0.05, asterisk). (H–J) For the genotypes indicated in the color key, embryos were heat shocked at the indicated times and fixed several hours later to stain for ngn1 (H and I) or basal relocalization of GM130 (J). Data show the mean and SD of the total number of stained cells in the otic epithelium or delaminated cells outside the otic vesicle (counted from the serial sections, n = 3 otic vesicles per time point). Asterisks indicate significant differences from control specimens (P < 0.05). (K–V) EMT markers in cross-sections (dorsal up, anterior left) passing through the neurogenic domain of control embryos, gsc mutants, or hs:gsc embryos immunostained for p-Paxillin (K–P) or GM130 (red) and DAPI (blue) (Q–V). Controls and transgenic embryos were heat shocked at 22 hpf. Boxed regions in K–M are magnified in N–P, and boxed regions in Q–S are magnified in T–V. White arrows indicate elevated basal staining in cells undergoing EMT. (Magnification: A, B, D, E, K–M, Q–S, 640×; C and F, 512×; N–P, T–V, 2,000×.)
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