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Fig. 3
Mortality in Sec23b-deficient ZF between 18 and 21 d is rescued by Sec23a. (A and B) sec23b heterozygous (sec23b+/−) ZF with a 53-bp deletion were generated with CRISPR/Cas9. Binucleated erythrocyte counts from peripheral blood of ZF offspring from a sec23b+/− × sec23b+/− intercross were evaluated by two independent investigators blinded to the ZF genotype. (C) sec23b−/− ZF exhibit indistinguishable o-dianisidine staining compared with WT clutchmate controls. Scores 1–3 correspond to staining intensities (3 = highest staining intensity). (D) sec23b−/− ZF (generated from sec23b+/− intercrosses) die between 18 and 21 d. (E) H&E stains of sec23b−/− and WT ZF at day 16. sec23b−/− ZF appear histologically normal. (Magnification: 10×.) (F) One-cell–stage embryos generated from sec23b+/− ZF intercrosses were injected with a vector (designed to integrate in the ZF genome) that expresses Sec23a and GFP or GFP alone as control. Genotyping at 4 wk of age demonstrates rescue of sec23b−/− mortality by Sec23a. (G) PCR genotyping assay demonstrating 2 sec23b−/− ZF, expressing Sec23a from a ubiquitin promoter, alive at 4 wk of age.