The early endothelial expression of sox18 and sox7 is affected in cloche mutants but not in scl-morphants. The expression of sox7 and sox18 was analyzed by ISH in pools of embryos from cloches5 heterozygotes clutches at 6 to 8 somites (A,B,E,F) and 24 hpf (C,D,G,H). Control hybridizations carried out with gata1 or cdh5 probes, at the 2 developmental stages, confirmed that cloche mutant embryos were present at the expected Mendelian frequencies. Images of cloche mutants (B,F) (with sox7 and sox18 probes, respectively) and siblings (A,E) (with sox7 and sox18 probes, respectively) are shown in dorsal views, anterior to the left; the expression of both genes in the PLM is lost in the mutants. The expression of sox7 and sox18 in nonvascular domains is unaffected in cloche mutants at 24 hpf, while most endothelial expression is lost (D,H) (clo embryos with sox7 and sox18 probes, respectively); (C,G) (siblings); lateral views, anterior to the left. The expression of sox7 and sox18 was analyzed by ISH in control embryos injected with std-MO and in scl-morphants at 6 to 8 somites (I,J,M,N) and 22 hpf (K,L,O,P). Control hybridizations on scl-morphants were carried out with gata1 at both developmental stages. Comparable levels of sox7 and sox18 expression in the PLM are shown in control embryos (I,M) (with sox7 and sox18 probes, respectively) and in scl-morphants (J,N) (with sox7 and sox18 probes, respectively); dorsal views, anterior to the left. Expression of sox18 (20 of 23) but not sox7 (19 of 23) is detectable in the PCV region in scl-morphants at 22 hpf (L,P) (with sox7 and sox18 probes, respectively); std-MO–injected embryos are shown as a control (K,O) (with sox7 and sox18 probes, respectively); lateral views, anterior to the left. White arrowhead indicates DA; black arrowhead, PCV; black arrow, caudal vein (CV) region; and white asterisk, ICM.
