Fig. 2

Thermal challenges were the same as described above. Sample size was 30 for each thermal challenge and at least three biological replicates were performed. A: Kaplan-Meier curves of three genotypes (dusp1^-/-, dusp1^+/-, and WT) treated by 8 °C exposure. B: Quantified apoptotic signal in gills under cold exposure analyzed by ImageJ software. Student’s t-test, ^*: P<0.05; ^**: P<0.01. C: TUNEL assay showing apoptotic signal in gills under 8 °C treatment. Scale bar: 100 µm. D: Kaplan-Meier curves of three genotypes (dusp1^-/-, dusp1^+/-, and WT) under 38 °C exposure. E: Quantified apoptotic signal in gills under hot exposure analyzed by ImageJ software. Student’s t-test, ^**: P<0.01. F: TUNEL assay of apoptosis in gills under hot (38 °C for 4 h) treatment. Scale bar: 100 µm. G: Differences in upper and lower lethal temperature tolerance between WT and dusp1^-/- zebrafish. LOE indicates loss of equilibrium. Half survival rates (i.e., LOE rate) of dusp1^-/- fish occurred at 10 °C and 36 °C, respectively, under cold and heat challenges, while WT fish exhibited half survival rates at 8 °C and 38 °C, respectively. One-way ANOVA, ^*: P<0.05; ^**: P<0.01; ^***: P<0.001. H: Rescue of dusp1^-/- mutant by zebrafish dusp1 mRNA (Ad-dusp1). Adding dusp1 mRNA restored the survival rate of embryos under cold (8 °C) and hot (38 °C) treatment. The same amount of GFP mRNA (Ad-ctrl) and dusp1^-/- embryos without injection were used as controls. One-way ANOVA, ^***: P<0.001.