(A) Structure of the zebrafish bag3 gene and protein. Exon 2 is the target for the CRISPR/Cas9 gene editing in zebrafish bag3. The CRISPR/Cas9-induced mutation (19 bp deletion) in bag3 is shown in bag3 mutant DNA sequencing chromatogram. The 19 nucleotides deletion in bag3-/- leads to a frame shift, the introduction of a premature stop codon and thereby the premature termination of Bag3 translation, as demonstrated by the alignment of the Bag3-/- and Bag3+/+ aminoacid sequences (only partial aminoacid sequence shown) (B-C) Immunoblot analysis of 72 hpf bag3+/+ embryo protein lysates compared to lysates obtained from bag3-/- clutchmates with antibody against zebrafish Bag3. The figure shows one representative immunoblot from three independent experiments (N = 3, mean ± SD, P<0.0001 determined using two-tailed t-test). (D) Quantitative real-time PCR of bag3+/+ and bag3-/- embryos at 72 hpf shows significant downregulation of bag3 mRNA levels in bag3-/- embryos (N = 3, mean ± SD, P = 0.0004 determined using two-tailed t-test).