gad67 expression in KA′ and KA′ cells is differentially dependent on tal2 and olig2. (A,B) Zebrafish embryos injected with a mixture of mismatch morpholinos (A) or a cocktail of morpholinos directed against nkx2.2a, nkx2.2b and nkx2.9 mRNA (B). The nkx2 cocktail abolished gad67 expression in KA′ cells (arrow) in the lateral floor plate (B). gad67 expression in KA′ and VeLD cells (arrowhead) was not affected by the knockdown of the Nkx2 genes. (C,D) Embryos injected with a mismatch morpholino (C) or with a morpholino directed against tal2 mRNA (D). gad67 expression in KA′ cells (arrow) was abolished in the tal2 morphants, whereas gad67 expression in KA′ and VeLD cells (arrowhead) appeared to be normal. (E,F) Embryos injected with a mismatch morpholino (E) or a morpholino directed against olig2 mRNA (F). The strong gad67 expression in dorsally located cells (arrowhead) was abolished by knockdown of olig2. Expression in KA′ cells (arrow) and the low-level expression in what are presumably V2 interneurons was not affected by knockdown of olig2 expression. (G,H) Embryos injected with either a mix of tal2 and olig2 mismatch control morpholino (G) or with morpholinos directed against tal2 and olig2 mRNA (H). Co-injection of the tal2 and olig2 morpholinos abolished gad67 expression in both the KA′ (arrowhead) and KA′ (arrow) interneurons. Expression of gad67 in some dorsally located cells, which probably represent V2 interneurons expressing gad67 at low levels, still persisted in the spinal cord of double-injected morphants. Embryos were 24 hpf. Anterior left, dorsal up. Scale bar: 25 μm.
|
