Fig. 5. HIF-1 DNA-binding activities in the liver (A), heart (B), gills (C), and kidney (D), of fish exposed to hypoxia at 26°C, 18°C or 8°C. Results are shown as fold increase compared to levels in normoxic fish at 26°C and are means ±s.e.m. of 10 fish. Temperature has a significant effect on hypoxic activation of HIF-1 in the heart (P<0.05), gills (P<0.01) and kidney (P<0.001) of crucian carp (two-way ANOVA). *Significant difference to normoxic fish at 26°C (for P-values, see Fig. 2), significant difference (P<0.05, P<0.01 and P<0.05 for heart 6 h hypoxia, heart 24 h hypoxia and gills 48 h hypoxia, respectively) to normoxic fish at the same temperature, significant difference (P<0.05, P<0.05 and P<0.001 for heart, gills and kidney, respectively) to fish exposed to hypoxia for 24 h at the same temperature (Holm–Sidak post test).