Fig. 7

(A) 3D rendering generated using light sheet movies of Runx:mCherry;dbh:GFP double transgenic larva shows mCherry⁺ clusters (dotted ovals) in close proximity to GFP⁺ cells. DA, dorsal aorta. (B) Oblique slice through the 3D volume shows GFP⁺ extensions from the dbh:GFP⁺ cells into the mCherry⁺ hematopoietic stem and progenitor cell (HSPC) clusters. (B’) Detail of the boxed region in B shows contact formation between the GFP⁺ extensions and mCherry⁺ HSPCs (white arrowheads) in all three planes. (C) Quantification showing significantly reduced number of Runx:mCherry⁺ HSPCs in 6-hydroxydopamine (6-OHDA)-treated transgenic larvae compared to DMSO controls. Unpaired t test with Welch’s correction. DMSO vs. 250 μM 6-OHDA, p=0.0003; DMSO vs. 300 μM 6-OHDA, p=0.0002. Sample size (n), DMSO, n=13; 250 μM 6-OHDA, n=18; 300 μM 6-OHDA, n=15. Number of biological replicates = 3. (D) The ultrastructure of a dbh:GFP⁺ cell (labeled green) in proximity of a cell with HSPC-like morphology (labeled magenta) (white arrowheads). Surrounding tissues are labeled, and the dbh:GFP⁺ cell HSPC pair is posterior to the glomerulus, dorsal to pneumatic duct, pronephric tubule and intestine, and ventral to the notochord. (D’) Higher magnification shows the dbh:GFP⁺ cell-HSPC pair is only three-cell diameters from the vessel lumen (white area). (D’’) Full resolution detail of the dbh:GFP⁺ cell-HSPC pair showing contact formation. Abbreviations: D, dorsal; V, ventral; A, anterior; P, posterior.