Figure 6.

Overexpression of Myc-Lin7c caused apparent neurulation defects at the 20-ss but not before the 10-ss. The dlx3 in situ staining was used to mark the boundary of the neural plate. The otic precursor cells or otic vesicles are indicated with opposing arrows. A, Injection of GFP mRNA as a control did not affect neurulation, as suggested by normal dlx3 staining at the 5-, 10-, and 20-ss. Arrowheads indicate the olfactory placodes. B, At the 5- and 10-ss, dlx3 staining did not show apparent developmental defects of neurulation in embryos coinjected with Myc-Lin7c and GFP mRNAs (the latter served as a marker for injection and expression). Arrowheads indicate the olfactory placodes. C, At the 20-ss, overexpression of Myc-Lin7c caused defects in neurulation as suggested by the widening of the neural tube field and shortening of the anterior–posterior axis. In addition, the ectopic positioning of otic vesicles or olfactory placodes was observed in some embryos. Eight embryos of different levels of effects were presented, with the mildest at the upper left corner and the most severe one at the bottom right corner. D, The distance between the left and right dlx3-positive otic vesicles was measured and compared at the 5-, 10-, and 20-ss. The embryos with milder GFP expression (one plus sign) and stronger GFP expression (two plus signs) were analyzed separately. At the 20-ss, 52 out of the 73 myc-lin7c mRNA injected GFP++ embryos showed ectopic or missing otic vesicles and were not measured (*). Error bars stand for SDs. Inj., Injection.