Neurotransmitter and neuropeptide phenotypes in tal1, gata3, and gata2a mutants. Lateral views of gad, sst1.1, and urp1 expression in 24 h WT sibling (A,D,G,J,L,N) and tal1 (B,K), gata3 (E,M), and gata2a (H,O) mutants. Dorsal, top; anterior, left. Cross-sectional schematic indicating positions of KA″, KA′, and V2b neurons (P). Scale bars (A) = 50 microns (A,B,D,E,G,H); (J) = 50 microns (J–O). Dashed lines indicate ventral limit of spinal cord. Mean number of cells expressing gad in each D/V row of spinal cord region adjacent to somites 6–10 in WT and mutant embryos (C,F,I). For tal1 and gata3 mutant results (C,F) the approximate proportions of medial and lateral row 3 cells are indicated by horizontal lines separating the number of medially-located cells (bottom and indicated with an “M”) from the number of laterally-located cells (top and indicated with a “L”). All of the remaining row 3 cells in these mutants are lateral, consistent with them being V2b cells. More dorsal (row 4 and above) cells expressing gad in tal1 mutants (B) are only weakly stained and are in a different focal plane to the strongly stained KA″ cells, so they are harder to see. All counts are an average of at least 4 embryos. Error bars indicate SEM. Statistically significant comparisons are indicated with brackets and stars. ***P < 0.001, *P < 0.05. For P-values see Supplementary Table 3.
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