Fig. 3. The DN-RAR
2a acts in a dominant negative fashion. (A)
DN-RAR
2a is able to block induction of an RA-responsive luciferase
reporter gene (tk-[ßRARE]2-luc). Co-injection of
DN-RAR
2a RNA completely abolishes the response of the reporter gene to
RA. Graph shows fold-induction relative to reporter alone; six embryos were
used for each experimental condition and assays were carried out in duplicate
and averaged. (B-E) hoxa4a expression, 10 hpf, lateral view.
(B) Normal embryo. (C) hoxa4a expression is upregulated and extended
towards the anterior after 1 hour treatment with RA. (D) DN-RAR mRNA injection
blocks hoxa4a expression. (E) DN-RAR blocks the ability of RA to
activate hoxa4a expression.