Wild-type worms induce the intestinal expression of a
gcs-1::gfp transcriptional reporter within 5 hours of infection with PA14 (One-way ANOVA, F = 13.33; Tukey HSD test, P<0.01)(Fig 3A, 3B and 3E). Note that this change in gene expression occurs rapidly, before visible physical symptoms appear. In contrast,
fshr-1(
ok778) mutant worms fail to induce expression of
gcs-1::gfp upon PA14 infection (Fig 3C-3E). These data, in combination with the microarray (Fig 1E), indicate that
fshr-1 is required for the early activation of the host's protective oxidative stress response upon infection.