Fig. 3

Etv2 depletion by caged MO photoactivation inhibits lymphangiogenesis. (A-H) Etv2 depletion by caged MO photoactivation inhibits thoracic duct development in fli1a:GFP; kdrl:mCherry (A-D′) and TgBAC(prox1a:KalT4-UAS:uncTagRFP) (E-H) reporter zebrafish larvae at 4.5 dpf and 7 dpf, respectively. (A,E) Control uninjected larvae with normal thoracic duct (TD) below the dorsal aorta (DA). (B,F) Embryos injected with etv2 MO and caging strand solution (hereafter called “photomorph solution”), but never exposed to UV photoactivation, develop normal thoracic duct similar to uninjected controls. (C,G) Embryos injected with photomorph solution and exposed to UV photoactivation at 6 hpf (shield stage), develop abnormal vasculature (C) and no or discontinuous thoracic duct (G) compared to control embryos as expected. (D,H) Embryos injected with photomorph solution, exposed to UV photoactivation at 24 hpf, develop normal vasculature compared to control embryos but discontinuous or absent TD (asterisks). (I-L′) Etv2 is required for the formation of parachordal lymphangioblasts, as observed in fli1a:GFP; kdrl:mCherry reporter zebrafish larvae at 56 hpf. (I) Control uninjected larvae. (J) Embryos injected with photomorph solution, but never exposed to UV photoactivation, develop normal parachordal lymphangioblasts (PL, arrowheads) similar to uninjected controls. (K) Embryos injected with photomorph solution, and UV photoactivated at 6 hpf (shield stage), develop abnormal vasculature, while PLs cannot be visualized due to abnormal branching of ISVs. (L) Embryos injected with photomorph solution, and UV photoactivated at 24 hpf, develop normal vasculature compared to control embryos while PLs are absent (arrowheads). A′-D′ and I′-L′ show magnified areas indicated by boxes in A-D and I-L. Each experiment has been repeated at least three times. Number of larvae showing a displayed phenotype out of the total number of larvae is shown in the upper right corner.