MPO and infection: To study neutrophil-microbe interactions, we injected fluorescent E. coli into Tg(mpx:GFP) embryos, which expressed green fluorescent protein (GFP) under the control of the neutrophil-specific promoter of myeloperoxidase (mpx) (Renshaw et al., 2006), and we then imaged neutrophil behaviour by using confocal time-lapse microscopy from 2 hours post-infection (hpi).