Fig. 2.

Manifestations of nephron dysfunction during systemic infection in zebrafish. A: representative images of septic larvae showing larval edema in the pericardial area (red arrows) at 2 days after 300-CFU Edwardsiella tarda injection. B: after injection with 300 CFU E. tarda for 2 days, septic vs. control larvae were injected with FITC-dextran (40 kDa) and subjected to fluorescence intensity measurements in the pericardium under the stereomicroscope. Dextran excretions at 24 h post-dextran injection were compared with intensities at 3 h after the injections in the same animal. Representative images of fluorescence accumulation around the zebrafish pericardium (red arrows pointing to yellow triangular area) at the two time points are shown. C: bar graph shows quantified fluorescence intensities (means ± SE) at the two time points; n = 5 larvae per group. The scatterplot (presented as means ± SE) displays nephron clearance index (FITC intensity_3h – FITC intensity_24h) normalized by the larval heart rate. D: impaired endocytosis of dextran by the adult zebrafish nephron tubule depending on severity of infection. Representative images show lower nephron fluorescence accumulations in the infected animal nephrons compared with control, with the least seen in the severely infected animal. High-magnification images show endocytosis-defective cells in the infected animal nephrons (yellow arrows). The corresponding quantified fluorescence intensities are shown in the bar graph (means ± SE). Statistical analysis suggests significant differences among groups. n = 3 animals per group. C, control; HM, high magnification; hpi, hours postinjection; INF, infected; LM, low magnification; Mod, moderate; Sv, severe. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.