Fig. 6

The zebrafish Stx4^R241W variant is hypomorphic

(A) Schematic of constructs used to generate transgenic zebrafish expressing WT Stx4 (actb2:stx4-IRES-GFP) and the zebrafish Stx4^R241W variant (actb2:stx4^R241W-IRES-GFP), which is equivalent to the patient 1 STX4^R240W variant.

(B–E) Images of 72 hpf WT and stx4 mutants hemizygous for the actb2:stx4-IRES-GFP and actb2:stx4^R241W-IRES-GFP transgenes. Scale bar, 200 μM.

(F and G) Heart rates determined from ventricular regions of interest of 72 hpf WT and stx4 mutant larvae lacking and hemizygous for actb2:stx4-IRES-GFP or actb2:stx4^R241W-IRES-GFP. Data are represented as the mean ± SEM, n = (F) 4–14 and (G) 10–18 larvae/group, respectively, one-way ANOVA, ∗∗∗∗p < 0.0001.

(H) Heart rates from ventricular ROIs determined from 72 hpf WT and stx4 mutant larvae lacking and hemizygous for actb2:stx4^R241W-IRES-GFP treated with either 1% DMSO/embryo water (control) or 20 μM Bay K-8644. Data are represented as the mean ± SEM, n = 8–10 larvae/group, one-way ANOVA, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.