Fig. 2.

HEK-293T cells were co-transfected with pTK-Renilla luciferase control along with an HRE-luciferase reporter construct and HIF-1α (or HIF-2α) expression plasmid. The cells were divided into two groups and exposed to 21% O₂ or 1% O₂ for 18 h. The data are reported as the relative luciferase activities. (A) The increase in luciferase activity stimulated by HIF-1α of fish from different lineages due to hypoxia. (B) The increase in luciferase activity stimulated by HIF-2α of fish from different lineages due to hypoxia. (C) Comparison of the activity toward common targets between the HIF-1α and HIF-2α genes of Senegal bichir. (D) Comparison of the activity toward common targets between the HIF-1α and HIF-2α genes of Namucuo naked carp. B1, Senegal bichir HIF-1α; G1, shortnose gar HIF-1α; Y1, bighead carp HIF-1α; N1, Namucuo naked carp HIF-1α; B2, Senegal bichir HIF-2α; and N2, Namucuo naked carp HIF-2α.