Fig. 4

flt4 expression is altered in arterial cells of sox7 mutants. (A-C) sox7^hu5626 siblings (upper panel) and mutants (lower panel). (A) In situ hybridization for sox18, hey2 and flt4 in sox7^hu5626 heterozygous and mutant embryos at 20hpf (dorsal view). sox7^hu5626 mutants display elevated flt4 expression levels in the LDA (arrow). (B) Dorsal view of flt4:mCitrine (flt4:mCit)-positive sox7^hu5626 heterozygous and homozygous mutant at 26hpf showing elevated mCitrine expression in the LDA of sox7^hu5626 mutant (arrow) compared with sox7^hu5626 siblings. (C) Lateral view of the trunk region of sox7^hu5626 siblings and mutants with in situ hybridization for sox18, hey2, efnb2, notch3 and flt4 at 24-27hpf. sox7^hu5626 mutants display higher flt4 expression in DA and ISVs (arrows) compared with siblings. (D) Quantification of 20-24hpf embryos based on their flt4 expression levels (in situ hybridization) in the LDA. Seventy-three percent of sox7^hu5626 mutants have high expression of flt4 in LDA region at 20hpf (total of 30 embryos). (E) Quantification of 24-27hpf embryos based on their flt4 expression levels (in situ hybridization) in the trunk. Fifty-eight percent of sox7^hu5626 mutants have elevated flt4 expression, which was never observed in siblings (total of 57 embryos). (L)DA, (lateral) dorsal aorta; (P)CV, (posterior) cardinal vein; ISV, intersegmental vessel.