Fig. 3

NF-κB is activated in vivo in the swimbladder upon infection and activation is enhanced by interaction of C. albicans with the epithelium. (A–F) Cohorts of 20 NFκB:EGFP fish were infected by immersion with C. albicans CAF2-dTomato and imaged by confocal microscopy at 5 dpi. (A,B) In vivo NF-κB activity in low-level-infected (A) and uninfected (B) swimbladder. (C–F) Ex vivo dissected swimbladder with low-level infection. (C) Fully inflated dissected swimbladder with (D) yeast cell inside a phagocyte (yellow arrow), and (E) partially inflated dissected swimbladder with (F) yeast cells in direct contact with epithelium (white arrow) and inside a phagocyte (yellow arrow). Animated z-stack of panel C is shown in supplementary material Movie 3, and zoomed z-stack is shown in supplementary material Movie 4. Animated z-stack of panel E is shown in supplementary material Movie 5, and zoomed z-stack is shown in supplementary material Movie 6. (D,F) Magnifications of C and E (white boxes). (G) Schematic representation of the epithelial response to the presence of extracellular fungi (E,F) or phagocytosed fungi only (C,D). Presence of extracellular C. albicans and epithelial cell EGFP (green) expression at 37 infection foci was quantified in images from 13 different fish in four independent experiments. There is a significantly higher proportion of cases of detectable EGFP in epithelial cells when there are extracellular fungi present. Fisher’s exact test; *P<0.05. Scale bars: 100 μm (A–C,E) and 20 μm (D,F). Maximum projections of n slices: n=11 (A), n=8 (B,C) and n=1 (D,F). Images are representative of four independent experiments.