We used the Tg(mpeg1:mCherry-F) line in which macrophages are fluorescently labeled, and assessed phagocytic activity of macrophages by determining the percentage of Mm that were internalized by macrophages in the yolk sac area within 5-25 min after infection based on previous analysis of the kinetics of this response (64) (Figures 3A–C). The gene discussed is MPEG1; the disease is infection.