Actin dynamics are required for gradient detection. In support of Fig. 4. (A) Scheme of a zebrafish larva indicating the TF wound (red) and area of imaging (blue). Left: Neutrophils in a Tg(mpx:PHAKT-EGFP) infiltrating the TF. Middle: Neutrophils losing polarity and motility after addition of LatB. Right: Addition of LTB4 and assessment of signaling response. (B) Scheme that shows the separation of cell into two parts, one towards the LTB4 and one away from LTB4. The line that separates the cell is perpendicular to the line that connects the center of cell and the center of the boundary of the larva edge. (C) Left: Neutrophils in a Tg(mpx:PHAKT-EGFP) infiltrating the TF. Red dashed line indicates the TF wound. Middle: Neutrophils lose motility post-LatB addition. Right: Neutrophils (white arrows) immediately after LTB4 addition. Scale bar = 15 μm. (D) Plot of neutrophil PH-AKT orientation (towards/away), within a time window of 3 min after LTB4 addition. n = 34 cells from 5 larvae. Two-tailed paired t test.