Fig. 6

haf^sk24 Is a Strong Loss of Function Allele of vmhc, a Ventricle-Specific Myosin Heavy Chain Gene with Expression Complementary to amhc. (A and B) Fluorescent in situ hybridization for vmhc (green) and amhc (red) in wild-type (wt) embryos at LHT ([A] 26 hpf, dorsal view) and expanded chamber ([B] 48 hpf, frontal view) stages. At all stages examined, vmhc is expressed in the ventricular myocardium [51]. In contrast, amhc expression is restricted to the atrial myocardium [28]. (C) Comparison of vmhc coding sequence in wt and haf^sk24 embryos reveals a C to T transition at position 3,094 that results in a premature stop codon in haf^sk24. (D and E) Whole-mount in situ hybridization depicts frontal view of vmhc expression in wt and haf at 48 hpf. vmhc expression is dramatically reduced in the haf mutant ventricle.