Figure 7. Hypoxic conditions prolong EBNA1's capacity to transactivate.

(A) Transactivation by EBNA1 is sustained under hypoxic conditions. C33a cells were co-transfected with an EBNA1-oriP expression plasmid and the oriP-BamHI-Cp-luciferase reporter plasmid. Transfected cells were split six hours post-transfection, and grown under normoxic (filled circles) or hypoxic conditions (filled squares). Luciferase expression was measured at the indicated time-points, and is expressed relative to the luciferase expression observed under normoxic conditions 48 hours post-transfection. (B) Oxygen levels do not affect oriP-plasmid replication and maintenance. A Southern blot was performed to examine the levels of replicated (DpnI-resistant) oriP-BamHI-Cp-luciferase plasmid recovered after six days under normoxic or hypoxic conditions. The arrowhead indicates replicated, full-length oriP-BamHI-Cp-luciferase. (C) Environmental oxygen levels do not alter the activity of DBD-VP16. C33a cells were transfected with a DBD-VP16 expression plasmid and the FR-TKp-luciferase reporter plasmid. Luciferase activity was measured three days post-transfection in cells exposed to normoxic or hypoxic conditions.