Zebrafish hif3a facilitates hypoxia tolerance. (A) Representative images of hif3a−/− larvae and WT (hif3+/+) larvae (30 larvae for each, 90 larvae in total; 3 dpf), subjected to normoxia (21% O2) or hypoxia (2% O2) for 12 h. The dead larvae (marked by red arrows) exhibited lack of movement, absence of blood circulation and bodily degeneration. (B) Representative images of living and dead zebrafish larvae. (C) Hif3a−/− adults were more sensitive to hypoxia (5% O2) compared with their WT siblings. Survival of hif3a+/+ (left flask) and hif3a−/− (right flask) (6 mpf) after 0 min, 30 min, 46 min, 50 min and 54 min in hypoxic conditions (5% O2) (three zebrafish for each, three replicates). Red arrows indicate dying zebrafish. (D) The survival rate curve of hif3a−/− larvae and their WT siblings. The oxygen concentration of the hypoxia workstation was adjusted to 2% before experimentation. The dead larvae were counted once every two hours (100 larvae). (E) Oxygen consumption rate was lower in hif3a−/− than in their WT siblings (6 mpf). The experiments were repeated at least three times. Error bars indicate s.e.m.; ns, not significant; *P<0.05; **P<0.01; ***P<0.001 (unpaired, two-tailed Student's t-test).
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