Generation of WHIM-GFP transgenic larvae. (A) Alignment of the C-terminal tails of human CXCR4 with zebrafish CXCR4b and WHIM-truncated zebrafish CXCR4b. Note conservation of serine residues. Arrow marks an identified WHIM truncation mutation. (B) Fluorescence images of human embryonic kidney cells expressing GFP (first column), CXCR4b-GFP (second column), or WHIM-GFP (third column) after incubation with human SDF1 (bottom row) or vehicle control (top row). (C) Schematic of Tol2-MPO:zCXCR4b-WHIM-GFP vector injected to generate WHIM-GFP transgenic lines. (D) Schematic of 3-dpf zebrafish larvae. Boxed region is approximate area magnified in panel E. (E) Fluorescence image of the CHT region of a 3-dpf WHIM-GFP larvae. (F-G) High-magnification image of GFP-expressing neutrophils from the CHT of a MPO:GFP (F) and a WHIM-GFP (G, blow up of box in larva from panel E. Note membrane expression in panel G. Bar = 50 μm (E); 20 μm (B); 10 μm (F-G).