Sf3b1 regulates erythrocyte number and maturation. (A-D) In situ hybridization of early globin hbbe3 (A-B) and o-dianisidine staining (C-D) in siblings (Sib) (A,C) and sf3b1 mutant (mut) (B,D) at 48 hpf. For mutants, example of a high signal embryo is shown on the left and an example of a mutant with low signal is shown on the right. Numbers in the lower right denote number of embryos that displayed a similar phenotype to the image. Graphs on the right denote the percentage of embryos with the designated phenotype. (E) Schematic representing the experimental flow to measure hbbe3 levels in o-dianisidine–positive erythrocytes by sequential staining. O-dianisidine staining was performed first followed by hbbe3 in situ hybridization in the same embryo, thus consecutively labeling oxygenated and immature erythrocytes. (F) O-dianisidine staining (top) followed by in situ hybridization of hbbe3 (bottom) in the same sf3b1-mutant embryos at 48 hpf (2 examples shown). Inset to the right shows a higher magnification view of area boxed in the image on the left. (A-D,F) In situ stain nitroblue tetrazolium, o-dianisidine stain; original magnification ×6, inset ×12. Med, medium.