Figure 2

Defects of hydrogen peroxide in E. coli and zebrafish embryos. (a) Schematic describing the onset of defects due to hydrogen peroxide exposure in the E. coli and zebrafish embryos. (b,c) Concentration-dependent (b) and time-dependent (c) viability of E. coli treated with the H₂O₂ solution. (d) Gross morphology of the wild type zebrafish embryos treated with H₂O₂ at 96 hpf from a lateral view. The scale bar represents 200 µm. (e) Determination of the sinus venosus (SV) to bulbus arteriosus (BA) length per body length ratio at 96 hpf. (f) TUNEL assay of wild type zebrafish embryos at 72 hpf treated with H₂O₂. The scale bar represents 100 µm. (g,h) Optical observation of Tg(flk1:EGFP) (g) and Tg(cmlc2:EGFP) (h) zebrafish embryo phenotypes at 72 hpf upon treatment with H₂O₂. The scale bar represents 100 µm. (i) Assessment of heart functionality based on zebrafish embryo heart rates following treatment with H₂O₂ at 48 hpf, 72 hpf, and 96 hpf. Results from the three separate experiments are presented as heartbeat numbers compared to the control. Means ± SEM (n = 4). ∗p < 0.01 from the control group. (j) Tg(lfabp:DsRed) zebrafish embryo phenotype at 96 hpf upon treatment with H₂O₂. The angle of the developing liver was measured by ImageJ software analysis through the part shown at the dotted line. The scale bar represents 100 µm. (k,l) Comparative liver sizes (k) and angles (l) based on eye-to-otolith in the Tg(lfabp:DsRed) zebrafish embryos treated with H₂O₂. Results from the three embryo measurements are presented as liver sizes and angles compared to the control. ImageJ (version 1.52a, https://imagej.nih.gov/ij/index.html, Wayne Rasband National Institutes of Health, USA) was used for the quantification of sizes and angles of the liver.