Fig. 4

isl2a is required in angioblasts. (A–D) Tg(kdrl:GFP)^la116 cells derived from Tg(kdrl: GFP)^la116 embryos were transplanted into non-transgenic wild type (wt) or isl2a morphant (MO) recipient embryos. Cells transplanted from wild type donors into wild type recipients (A; blue bars; wt>wt) contribute to the artery, vein and ISAs. Cells from isl2a^{ATG MO} injected donor embryos transplanted into wild type recipient embryos (B; MO>wt) contribute less to the vein (green bars; J,L; p<0.02) while wild type cells transplanted into isl2a^ATG morphant recipient embryos (C; orange bars; wt>MO) do not differ statistically from wild type>wild type transplants in their contribution to the artery, vein and ISAs. (E–J) Expression of isl2a^Lim in wild type embryos results in stalled ISAs at 30 hpf (E: kdrl: GFP, F: Isl2^LimA2TagRFP, G: overlay) and fewer cells per ISA at 48 hpf (H: green Tg(fli: neGFP)^y7, red Isl2^LimA2TagRFP). (I) ISA stalling is similar at 30 hpf in Isl2^Lim injected embryos in two different vectors with different tagging systems. (J) The number of cells per ISA is significantly reduced in dominant negative injected embryos. (K). The number of cells per ISA is significantly increased with angioblast expression of isl2a. (L–O) Effect of upregulation of isl2a in angioblasts. The number of cells forming each ISA was counted in wild type control (L) and fli1a:isl2a (M) overexpressing embryos at 30 hpf. (N,O) Morphology of fli1a:isl2a overexpressing embryos is not distinguishable from wild type embryos and success of transgenesis can be verified expression of cmlc (cardiomyocyte light chain) driven GFP from the vector backbone (arrowhead) in the heart. Scale bars represent 50 µm for A-H, L–M, and H 100 µm for M-O.