Figure 1—figure supplement 1.

Figure 1—figure supplement 1. Characterization of endothelial marker and β-catenin reporter expression in zebrafish larval brain vasculature.

(A–A”) Dorsal views of a 10 days post fertilization (dpf) Tg(plvap:EGFP) zebrafish head immunostained for Glut1, an endothelial marker for the blood-brain barrier (BBB) state. Tg(plvap:EGFP)⁺ blood vessels formed in the diencephalic choroid plexus (dCP) and myelencephalic choroid plexus (mCP) were devoid of Glut1 immunoreactivity. (B–D) Magnified, merged images of the immunostained larva shown in (A”). Glut1 immunoreactivity was mostly detected in Tg(plvap:EGFP)^- blood vessels in the meningeal and brain parenchymal compartments. (E–F”’) Dorsal views of the 10 dpf Tg(plvap:EGFP);Tg(glut1b:mCherry) zebrafish heads immunostained for P-glycoprotein (Pgp) shows absent expression of both the Tg(glut1b:mCherry) transgene and Pgp immunoreactivity in the Tg(plvap:EGFP)⁺ Hy loop (E–E”’). While Pgp immunoreactivity overlapped with most Tg(glut1b:mCherry)⁺ blood vessels (E’, E”, F’, F”), Tg(plvap:EGFP)⁺ blood vessels were mostly devoid of Pgp immunoreactivity. Similar to Glut1 immunoreactivity (Figure 2C–D”), a rostral portion of the Tg(plvap:EGFP)⁺ hypophyseal artery (HyA) in proximity to the organum vasculosum of the lamina terminalis (OVLT) and the palatocerebral arteries (PLA) junction was devoid of both Tg(glut1b:mCherry) transgene expression and Pgp immunoreactivity (F–F”’). (G–K) Magnified, merged images of 6 dpf Tg(fli1:GAL4-Hsa.TCF7L2-2A-mCherry);Tg(UAS:EGFP);Tg(fli1:MYR-mCherry) larvae show endothelial β-catenin reporter expression in hindbrain central arteries (G, arrows). This high level of endothelial β-catenin reporter expression was not detected in strong Tg(plvap:EGFP)⁺ vasculature which forms in the dCP (H) and mCP (I) as well as in the Hy loop (K) and a rostral portion of the HyA (J). Scale bars: 50 µm in (A”) for (A–A”), in (B–D), and in (G–K); 25 µm in (E”’) for (E–E”’) and in (F”’) for (F–F”’).