Figure 2.

Targeting strategy and expression validation of Hand1A^126FS/+ mice. (A) Schematic of the Hand1 locus and targeting construct. Hand1 targeting arms¹⁰ were utilized to insert a loxP element-flanked Neomyosin cassette (Flox STOP Neo).³² The 3′ targeting arm includes the A126fs mutation. Upon Cre-recombination and removal of the Stop-Flox cassette, activates the Hand1^A126fs allele. (B) Southern blot analysis shows targeting frequency exceeding 50%. (C) E10.5 wholemount Hand1 ISH in control (Hand1^SF-A126fs/+), recombined (Nkx2.5^Cre/+; Hand1^A126fs/+), and compound Hand1 heterozygotes (Nkx2.5^Cre/+; Hand1^A126fs/fx) single-copy mutants. I2, mandibular component of the first pharyngeal arch; oft, cardiac outflow tract; rv, right ventricle; lv, left ventricle; u, umbilicus. Scale bar 150 μm.