her9 overexpression down-regulates ntl and partially rescues the cyc mutant floor plate. A-D: Wild-type embryos injected with hsp70:her9myc and heat shocked at shield stage, fixed at YPC stage (9.5 hpf), and probed for ntl expression (blue) and myc labeling (brown). A: Whole-mount, dorsal view and (B) transverse section at high magnification showing that her9myc expressing cells at the midline do not express ntl (arrowheads). C,D: Control wild-type embryos injected with hsp70:GFP and heat shocked at shield stage, fixed at YPC stage and probed for ntl expression (blue) and GFP labeling (brown). C: Whole-mount, dorsal view and (D) transverse section showing that GFP expressing cells at the midline do express ntl (arrowheads). E-G: Whole-mount, side views of 24 hpf embryos probed for col2a expression. Anterior is to the left. E: Floor plate and hypochord express col2a in wild-type embryos (arrows). F: Floor plate is absent in cyc mutant embryos (asterisk), but hypochord develops normally (arrow). G: cyc mutant embryos injected with hsp70:her9myc and heat shocked at shield stage develop floor plate cells (arrowheads). Scale bar = 40 µm in E-G; 100 µm in A,C; 20 µm in B,D.
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