Figure 3.

pou3f2a and pou3f2b Expression Is Reduced in sim1a Morphants and Is Eliminated in arnt2-Null Mutant Embryos

Representative lateral views of embryos stained for pou3f2a or pou3f2b expression by WISH at 48 hpf. Eyes have been removed to better visualize the staining in the NPO (indicated by white arrowheads and magnified views are shown in the insets).

(A and C) Control morpholino oligonucleotide (MO)-injected embryos showing normal expression of pou3f2a (n = 11) (A) and pou3f2b (n = 10) (C).

(B and D) sim1a MO knockdown reduces the level of pou3f2a (n = 9) (B) and pou3f2b (n = 12) (D) expression.

(E and G) Wild-type embryos showing strong pou3f2a (n = 7) (E) and pou3f2b (n = 13) (G) staining in the NPO.

(F and H) arnt2-null mutant embryos showing an absence of pou3f2a (n_wt = 7; n_het = 12; n_hom = 8) (F) and pou3f2b (n_wt = 13; n_het n = 28; n_hom = 18) (H) in the NPO.

(I and J) Both sim1 MO-injected embryos (I) and arnt2-null mutants (J) resulted in a significant number of embryos showing reduced (orange) or no (red) expression of pou3f2a and pou3f2b indicating that their expression in the NPO is dependent on functional sim1a-arnt2 heterodimers.