Figure 10.

nmr2 and nkx6 collaborate to inhibit eve expression.

(A–C) Stage 14 wild-type and mutant embryonic nerve cords stained for Eve, (D) a chart quantifies the number of Eve-positive lateral neurons in wild-type, nmr2^−/−, and nmr2^−/−;nkx6^−/− mutant backgrounds at stages 12 and 14, (E–J) immunofluorescent staining of Nmr2-, Nmr1-, and Nkx-6-positive neurons in the CNS of Stage 15 wild-type embryos. All images depict the ventral region of the CNS. (A) Stage 14 wild-type Eve expression pattern. (B) As shown previously, nmr2^−/− mutant embryos exhibit Eve-positive ectopic lateral neurons (arrows, see Fig. 1B). (C) nmr2^−/−;nkx6^−/− double mutant embryos exhibit increased numbers of Eve-positive ectopic lateral neurons throughout the nerve cord as compared with nmr2^−/− mutants (arrows). The nerve cords of nmr2^−/−;nkx6^−/− mutants also exhibit severe orientation defects that become pronounced at stages 15–16 (data not shown). (D) Each bar value represents the mean of 20 embryos scored for the number of Eve-positive ectopic lateral neurons observed throughout the nerve cord at stages 12 and 14. The error bars represent the S.E.M. and statistical significance was determined by One-way Analysis of Variance (ANOVA) where p** < 0.001 and p* < 0.01. (E–G) Nmr2 (green) and Nkx6 (red) exhibit a mutually exclusive expression pattern with the exception of one medial neuron per hemisegment that co-expresses Nmr2 and Nkx6 (merge, arrows). (H–J) Nmr1 (green) and Nkx6 (red) are also co-expressed in one medial neuron per hemisegment.